,note3 ,images of the original pages are
 available through        ,internet     
,archive4 ,see                          
https3_/_/archive4org_/details_/gasoline
motor#jjslaurich      ,transcriber's    
note3          ,text enclosed by        
underscores is in italics 7italics74    
,text in small capital letters has been 
changed to upper case4            ,,the 
,,gasoline ,,motor    by    ,,harold    
,,whiting ,,slauson1 ,m4 ,e4    ,author 
of ,the ,motor ,boat                    
,outing ,handbooks    ,new ,york        
,outing ,publishing ,company  ,,mcmxiii 
,copyright1 #aiac1 by  ,outing          
,publishing ,company    ,all rights     
reserved          ,,contents            
,i4 ,,types ,,of ,,motors               
#i        ,,ii4 ,,valves                
#bd       ,,iii4 ,,bearings             
#dc        ,,iv4 ,,the ,,ignition       
,,system         #fb         ,v4        
,,magnetos                    #hc       
,,vi4 ,,carburetors ,,and ,,their ,,fuel
  #ij       ,,vii4 ,,lubrication        

#aab      ,,viii4 ,,cooling             
#acj        ,,ix4 ,,two ,,cycle ,,motors
           #adh          ,,the          
,,gasoline ,,motor          ,,the       
,,gasoline ,,motor    ,,chapter ,i      
,,types ,,of ,,motors      ,there are   
certain events that must happen in a    
gasoline motor before  the engine will  
run of its own accord4 ,for instance1 to
 obtain  successive power impulses1 the 
charge must first be admitted to the    
cylinder and compressed2 it must then be
 ignited to form the explosion  that    
creates the force at the flywheel2 and  
the burned gases resulting  from this   
explosion must be ejected in order to   
clear the cylinder  for the new charge4 
,to accomplish this series of events1   
some motors  require four strokes1 while
 others do the business in two4 ,these  
are  popularly called four-cycle and    
two-cycle motors1 respectively4    ,a   
cycle1 of course1 can be any round of   
events1 such as a cycle of  years--at   
the end of which time the previous      

happenings are scheduled  to repeat     
themselves4 ,but in gas engine parlance 
a cycle is taken to  mean the round of  
events from1 say1 the explosion of one  
charge to the  ignition of the next4    
,thus1 it will be seen that the         
four-cycle motor  requires four strokes 
of the piston to accomplish its round of
 events1  and is1 properly1 a           
four-stroke cycle motor4 ,likewise1 the 
so-called  two-cycle motor requires two 
strokes to complete its cycle and should
  therefore be termed a two-stroke cycle
 motor4    ,if this longer terminology  
could be adhered to1 there would be less
  misunderstanding of the meanings of   
two- and four-cycle1 for when taken     
literally1 these abbreviated forms      
signify absolutely nothing4 ,usage      
seems to have made them acceptable1     
however1 and if the reader will but     
remember that four-cycle1 for instance1 
means four strokes per cycle1  the term 
becomes almost as simple as does        
four-cylinder4    ,it is evident that   

there are two strokes for each          
revolution of the  flywheel--one when   
the crank is forced down and the other  
when the  crank moves up4 ,as the piston
 is attached to the crank through the   
medium of the connecting rod1 the       
strokes are measured by the motion  of  
the piston4 ,thus1 since it requires    
four strokes of the piston to  complete 
the round of events in the four-cycle   
motor1 the explosions  occur only at    
every second revolution of the flywheel4
 ,in this  connection it must be        
remembered that we are dealing with but 
one  cylinder at a time1 for a          
four-cycle engine is practically a      
collection  of four single-cylinder     
units4    ,but even though the explosion
 in a four-cycle motor occurs only every
  other revolution1 the engine is by no 
means idle during the interval  between 
these power impulses1 for each stroke   
has its own work to do4  ,the explosion 
exerts a force similar to a hammer blow 
of several tons  on the piston1 and the 

latter is pushed down1 thus forming the 
first  stroke of the cycle4 ,the        
momentum of the flywheel carries the    
piston  back again to the top of its    
travel1 and during this second stroke   
all  of the burned1 or exhaust1 gases   
are forced out and the cylinder is      
cleaned1 or scavenged4 ,the piston is   
then carried down on its third  stroke1 
which tends to create a partial vacuum  
and sucks in the charge  for the next   
explosion4    ,on the fourth1 and final1
 stroke of the cycle the piston1 still  
actuated by the momentum of the         
flywheel1 is pushed up against the      
recently-admitted charge and compresses 
this to a point five or six  times      
greater than that of the atmosphere4 ,at
 the extreme top of this  last stroke1  
the spark is formed1 causing the next   
explosion1 and the  events of this cycle
 are repeated4    ,now1 inasmuch as on  
one up-stroke of the piston the charge  
must be held  tightly in place in order 
that it may be compressed1 and on the   

next  up-stroke a free passage must be  
offered so that the exhaust gases may   
be forced out1 it is evident that a     
valve must be used as a sentry  placed  
at the openings to restrain the         
desirable gas from escaping  and also to
 facilitate the retreat of the          
objectionable exhaust4  ,likewise1 the  
force of the explosion must be confined 
to the piston on  one down-stroke in    
order that all of the energy may be     
concentrated  at the crank1 while on the
 succeeding down-stroke a free passage  
must  be afforded to the charge so that 
it may be sucked in through the         
carburetor4 ,consequently a second valve
 must be used to control the  inlet     
passage on the down-strokes and prevent 
the escape of the force  of the         
explosion through an opening that was   
intended as an entrance  for the fresh  
charge4 ,thus valves are a necessity on 
all motors in  which successive similar 
strokes of the piston do not perform the
 same  operations4    ,as quadrupeds and

 bipeds form the two great divisions of 
the  animal kingdom1 so is the motor    
separated into the two main  classes of 
four-cycle and two-cycle engines4 ,even 
though to all  exterior appearances1 the
 two types of motors may be identical1  
the distinction1 to the engineer1 at    
least1 is as marked as is the           
difference between a stork and an       
elephant4 ,the difference is somewhat   
reversed1 however1 in that1 while the   
elephant has double the number of  legs 
of the stork1 the four-cycle motor has  
but one-half the number of  power       
impulses of its two-cycle cousin at the 
same speed4    ,in other words1 there is
 an explosion in each cylinder of the   
two-cycle  motor with every revolution  
of the flywheel1--instead of with       
alternate  revolutions1 as is the case  
with the four-cycle type4 ,but the      
number  of events necessary to produce  
each explosion must be the same in both 
types of motors1 and consequently it is 
only by doubling up and  performing     

several operations with each stroke that
 the two-cycle motor  can obtain a power
 impulse with each revolution of the    
flywheel4    ,starting with the ignition
 of the charge1 as in the four-cycle    
motor1  let us see how the events are   
combined in the two-cycle type so that  
all will occur within the allotted two  
strokes4 ,directly after the  explosion 
there is but one event that can happen  
if this force has been  properly        
harnessed1 and that is the violent      
downward travel of the  piston4 ,just   
before the bottom of this downward      
stroke is reached1  however1 an opening 
is uncovered through which the exhaust  
gases can  expend the remainder of their
 energy--which by this time has become  
greatly reduced4 ,immediately after this
 another passage is uncovered  and the  
charge is forced into the cylinder under
 pressure1 thus helping  to clear the   
cylinder of the remainder of the exhaust
 gases4    ,all of this takes place near
 the end of the down-stroke2 and at the 

beginning of its return1 the piston     
closes the openings previously          
uncovered for the passage of the exhaust
 gases and incoming charge1 and  then   
compresses the mixture during the       
remainder of its up-stroke4 ,thus  the  
suction stroke and the scavenging stroke
 of the four-cycle motor  are dispensed 
with in the two-cycle type and every    
downward thrust of  the piston is a     
power stroke4    ,the two-cycle motor   
has been used in several notable        
instances with  great success on motor  
cars1 but by far the larger majority of 
automobile power plants are of the      
four-cycle type4 ,in view of the        
wonderful simplicity of the two-cycle   
motor1 its small number of moving       
parts1 and its more frequent power      
impulses1 it may well be asked3  ,why is
 this not in more popular use on the    
motor car8 ,the four-cycle  motor has   
but one power stroke out of every four1 
while only alternate  strokes of the    
two-cycle motor consume power without   

producing any4    ,this would seem to   
indicate that1 for equal sizes and      
weights1 the  two-cycle motor would     
produce twice as much power as the      
four-cycle  type--and this is true      
theoretically4 ,but the four-cycle motor
 devotes  an entire stroke to forcing   
out the exhaust gases1 or scavenging1   
and  another entire stroke to drawing in
 a fresh charge1 and it is evident  that
 these operations can be done much more 
effectively in this manner  than when   
combined with several other events      
following each other in  such rapid     
succession as is the case with the      
two-cycle motor4 ,in  the two-cycle     
motor the incoming charge must be       
diluted to a certain  extent with the   
exhaust gases which have not been       
entirely expelled1  and the intake valve
 port is uncovered for so short a time  
that unless  there has been very high   
compression in the base1 the cylinder   
cannot  be entirely filled with the     
explosive mixture at high speeds4 ,this 

is described in greater detail in the   
last chapter of this volume4  ,thus1    
while admittedly simpler in construction
 and operation than the  four-cycle1 the
 two-cycle motor in its ordinary forms  
does not obtain  quite as high an       
efficiency from the fuel as does its    
more complicated  cousin4 ,each type has
 its distinct use1 however1 and in many 
instances  in which low initial cost and
 simplicity of design are more desirable
  than are economy of fuel and high     
efficiency of operation1 the  two-cycle 
motor stands supreme4    ,the sentries  
that stand guard over the passages      
through which the  gases make their     
entrance and exit may appear in a       
variety of guises1  but they determine  
the shape of the cylinders of a motor   
and divide  the four-cycle engine into a
 number of classes4 ,for instance1 if   
the  valves controlling the admission of
 the explosive mixture are placed on    
one side of the cylinders and those     
officiating over the exit of the        

exhaust gases are located on the        
opposite side1 the motor is known as    
the ,t-head type because of the shape of
 its cylinders4    ,all valves that are 
placed at the side of the cylinder must 
operate  in pockets so as not to        
interfere with the movement of the      
piston4  ,these pockets are cast with   
the cylinder and form a projection at   
its  side near the top4 ,when these     
projections are cast on opposite sides1 
a cylinder having the shape of the      
letter ,t is formed1 while if the       
valves operate on the same side1 the    
single projection forms a cylinder      
having the shape of the inverted letter 
,l4 ,hence cylinders having  valves on  
opposite sides are called ,t-head       
motors1 while ,l-head  motor is         
synonymous for an engine having valves  
on the same side4    ,when the valves   
are placed in the head1 there is no need
 of separate  pockets1 for these valves 
operate from above and do not interfere 
with the movement of the piston4 ,there 

may be a combination of these           
positions1 one set of valves being      
placed in the head and the others  at   
the side4 ,this is known as the inlet in
 head1 exhaust at side  type--or vice   
versa1 as the case may be4    ,the valve
 that has been in almost universal use  
in motor cars is known  as the poppet   
type1 as distinguished from the sliding 
and rotary  styles4 ,as evidenced by its
 name1 the poppet valve is pushed or    
lifted  from its seat1 and thus the full
 area of the opening to the passage is  
made available almost immediately4 ,the 
poppet valve is lifted by a cam1  the   
shape of which determines the relative  
speed of operation of the  valve1 and is
 returned to its seat by a stiff spring4
 ,the nature of the  contact that the   
valve makes with its seat depends upon  
the condition  of the surfaces and is   
the deciding factor as to whether the   
joint is  completely air-tight or not4  
,when the exhaust valve is opened1 its  
head is thrust directly in the  path of 

the hot1 out-rushing gases2 these same  
gases also swirl around  the edge of the
 seat4 ,the excessive heat and the      
particles of carbon  that are often     
found in the exhaust gases tend to      
corrode and build  a deposit on the     
edges of the valve and its seat1 thus   
eventually  preventing perfect contact  
from taking place4 ,this makes necessary
 the  grinding of the valves--an        
operation that is familiar to the       
majority  of motor car owners and       
drivers4    ,while the poppet valve     
motor is still used on the majority of  
automobiles1 a new and radical type of  
valve mechanism has been giving         
successful results4 ,this is known as   
the sliding sleeve type of motor1  and  
while it has been used for several      
seasons in ,europe1 #aiab saw  its      
adoption for the first time in ,america4
 ,the sleeve motor1 it must  be         
understood1 is of the four-cycle type1  
the events occurring in the  same order 
as on any ordinary automobile motor1 and

 the only difference  lies in the nature
 of the valves that control the openings
 of the  exhaust and inlet passages4    
,that this difference is great1 however1
  will be realized when it is understood
 that the valves consist of two         
concentric shells1 in the inner one of  
which the piston reciprocates4  ,in     
other words1 two hollow cylinders line  
the interior of the cylinder  casting   
and replace the poppet valves and       
pockets of the more familiar  type of   
motor4    ,these sleeves1 or shells1 or 
hollow cylinders--or whatever name it is
  chosen to give them--slide up and down
 in the same line of action as  that of 
the piston4 ,a port1 or slot1 is cut    
near the top on opposite  sides of each 
of the shells4 ,these four ports are so 
arranged that one  set opens directly   
opposite the intake passage1 while the  
other opens  by the exhaust manifold    
entrance4 ,when it is said that these   
ports  open1 it is meant that similar   
slots in the two sleeves come opposite  

each other1 or register1 so that an     
unobstructed passage for the gas  is    
offered4 ,the port in one sleeve may be 
opposite the intake pipe  entrance1 but 
if the slot in the other sleeve does not
 correspond with  this1 the passage is  
effectively closed4    ,thus it will be 
seen that the ports are opened and      
closed by the  movement of the sleeves  
in opposite directions4 ,for example1   
just  before the opening of the intake  
port1 the inner sleeves will be         
traveling upward while the outer shell  
moves downward1 and the slots  in the   
two shells will be opposite each other  
at the instant that they  pass the inlet
 pipe4 ,this gives a much quicker       
opening than would be  the case if one  
shell stood still while the other moved 
downward1 and  it is because the slots  
approach each other from opposite       
directions  that this motor can be run  
efficiently at high speeds4    ,inasmuch
 as this is a four-cycle motor and the  
explosions occur in each  cylinder but  

once during every two revolutions of the
 flywheel1 each  sleeve makes but one   
stroke for every two of the piston4 ,the
 sleeves  are operated by eccentrics    
attached to a shaft driven at a         
two-to-one  speed by the crank shaft of 
the motor1 and as they are well         
lubricated  there is but very little    
friction generated between them and the 
piston4 ,in fact1 it has been shown that
 the power required to operate  the     
sleeves1 when well lubricated1 is       
considerably less than that  consumed by
 the springs and valve mechanism of the 
poppet valve motor1  for the reason that
 the former type of valve does not open 
against the  pressure of the exhaust1 as
 is the case with the ordinary gas      
engine  valve4    ,besides the two- and 
four-cycle divisions1 a motor is known  
by the  arrangement of its cylinders and
 is classified as cylinders cast        
separately1 cast in pairs1 or triple    
cast1 according to whether  there are   
one1 two or three cylinders to a unit4  

,the last-named type  is not as common  
as are the pair-cast cylinders and of   
course can  only be used on six-cylinder
 motors4    ,when all of the cylinders  
of a motor are cast in one piece1 the   
engine  is known as a bloc motor4 ,this 
is a type that has come into popular    
use for small and medium-sized power    
plants during the past few years  on    
account of the simplicity of its        
construction and the smooth and  compact
 design that is rendered possible4 ,of  
course it may be argued  that1 with such
 a design1 the entire set must be       
replaced if a single  cylinder is       
damaged1 but castings have been so      
improved that an  accident or           
imperfection requiring the renewal of a 
cylinder is very  rare4    ,it is       
evident that1 beyond a certain size of  
cylinder1 a bloc casting  becomes too   
bulky to be handled conveniently1 and as
 the entire casting  must be removed    
when it is desired to reach the         
connecting rods1 crank  shaft1 or piston

 rings1 a motor so designed will seldom 
be found that  develops more than forty 
or fifty horsepower4 ,this type of      
casting is  found on some six-cylinder  
cars1 however1 but it is naturally only 
the  light sixes that will use such a   
motor4    ,above six-cylinders1 a motor 
is usually arranged with its power units
  set at an angle on either side of the 
vertical1 thus forming the  ,v-shaped   
motor4 ,several eight-cylinder motors   
are so constructed1 the  units being    
arranged four on a side and each set    
placed at an angle  of about thirty     
degrees from the vertical4 ,this gives  
the effect of  two four-cylinder motors 
placed side by side and operating on the
 same  crank shaft4    ,in order to make
 the motor as compact as possible1 the  
cylinders are  staggered2 or1 in other  
words1 the cylinders of one set are     
placed  opposite the spaces between the 
units of the other4 ,it will be seen    
that the ,v-shaped design of motor      
shortens the power plant and enables  it

 to be set in a much smaller space under
 the bonnet than would be the  case were
 the cylinders placed one in front of   
the other1 as in the  four- and         
six-cylinder types4    ,as a rule1 the  
two-cylinder1 four-cycle motor is of a  
different type  from its four- and      
six-cylinder cousins1 and is known as a 
horizontal  opposed engine4 ,in such a  
motor1 the cylinders are set lengthwise 
and the pistons operate opposite each   
other in such a manner that a  long1    
narrow1 and thin power plant is obtained
 that is especially  well-suited for a  
location under the body of the car4 ,in 
fact1 this  horizontal motor1 which may1
 of course1 be of the four-cylinder     
type1  is the only shape that can well  
be used under the body or seat of a     
touring car4 ,in some small runabouts1  
however1 the double-opposed  motor is   
used to good advantage under the forward
 bonnet1 as in the  big fellows4        
,there are1 of course1 many other       
features of design that serve to        

differentiate one automobile power plant
 from another1 but these are  details   
that do not serve to classify the motor1
 and the man who knows  whether his     
machine is two- or four-cycle2 poppet or
 sleeve valve2  separate1 pair1 or en   
bloc cylinder castings2 and ,t- or      
,l-head  shape will have at his fingers'
 ends distinctions that would have      
floored the salesman of a few years ago4
          ,,chapter ,,ii    ,,valves    
,it has been stated in the preceding    
chapter that the valves of the  gasoline
 motor are the sentinels placed on guard
 at the entrance to and  exit from each 
cylinder to make certain that the       
mixture follows its  proper course at   
the proper time4    ,therefore1 if we   
accept the definition that a valve is a 
mechanical  appliance for controlling   
the flow of a liquid or a gas1 strictly 
speaking no such thing as a valveless   
motor exists4 ,two-cycle  motors are    
sometimes said to be valveless because  
of the fact that  the movement of the   

piston automatically regulates the flow 
of the  exhaust and intake gases1 but in
 this case the piston is in reality  the
 valve4 ,on the four-cycle motor1       
however1 like events take place  only on
 alternate strokes in the same          
direction1 and consequently some        
controlling mechanism that operates but 
once for every four strokes of  the     
piston is needed to time the flow of the
 gases4    ,as has been stated in the   
previous chapter1 the most common form  
of  valve is known as the poppet type   
from the fact that its action is  a     
lifting one4 ,such a valve may be       
located in a projection cast on  either 
side of the top of each cylinder1 or it 
may be inverted from  this position and 
placed in the cylinder head4 ,when in   
the former  location1 the valve is      
opened by an upward push on the rod to  
which it  is attached at its center1    
while a valve placed in the cylinder    
head is  forced down to allow the escape
 or entrance of the exhaust or intake   

gases4 ,the ordinary type of poppet     
valve is somewhat similar in shape  to a
 mushroom1 having a very thin and flat  
head and a slender stem4 ,the  disc     
portion of the valve is known as its    
head1 while the rod forged  with the    
valve and by which the head is raised   
and lowered is called  the stem4    ,the
 projections cast in the cylinders of a 
,t-head or ,l-head motor1  and in which 
the valves are placed1 are known as the 
valve pockets4  ,valves so located are  
lifted by a direct upward push caused by
 the  rotation of a cam and are returned
 to their closed position by means of   
the extension of a stiff spiral spring  
surrounding each valve stem4 ,it  is    
only the outer edge of the lower side of
 the valve head that comes  in contact  
with the surrounding surfaces of the    
opening which is closed  when the valve 
is returned to its ordinary position by 
the spring4    ,this surface of contact 
surrounding the opening is known as the 
valve  seat1 and it is this1 together   

with the edge of the valve which rests  
against it1 that must be ground smooth  
in order to insure a tight joint  when  
the valve is closed4 ,on the majority of
 poppet valves the edge of  the head and
 the seat against which it rests are    
beveled to an angle  of approximately   
forty degrees in order to conform to the
 natural  direction taken by the gases  
when they are admitted or expelled4 ,in 
a  few cases1 however1 the seat angle is
 ninety degrees1 which means that  the  
edge of the head is ground flat1 or     
straight1 at right angles to  the stem4 
,one of the chief advantages found in   
the use of a poppet valve is the  fact  
that a large opening can be obtained    
after the valve head has  been raised   
but a comparatively short distance4     
,this means that the  valve stem need   
travel only a fraction of an inch       
between the full  open and the full     
closed position of the valve and that   
the operating  mechanism for obtaining  
this lift is simple4 ,practically every 

poppet  valve1 therefore1 is lifted by  
means of a cam1 which is a thick1       
irregularly-shaped piece of steel       
mounted on a shaft known as the cam     
shaft4 ,if the end of the valve stem1 or
 a rod connected to it1 is  held against
 the periphery of the cam while the     
latter is revolved by  its shaft1 the   
valve will be forced up1 or away1       
rather1 an amount  corresponding to the 
increase in distance between the        
periphery of the  cam at this point of  
contact and its axis4    ,in other      
words1 if the cam were a true circle    
with its axis passing  through its      
center1 there would be no motion of the 
valve1 for all  points of the periphery 
of a circle are at the same distance    
from the  center4 ,consequently a       
portion of the periphery of the cam is  
extended  in the shape of a nose1 the   
projection of this beyond the smallest  
diameter of the cam being the distance  
that the valve will be lifted  when this
 point of the cam surface comes in      

contact with the stem or  push rod4 ,the
 broader1 or more blunt1 the nose of the
 cam1 the longer  will the valve remain 
open as the cam shaft is revolved1 while
 the  slope of the sides of the nose    
determines the rapidity with which the  
valve will be pushed out and back4      
,inasmuch as the valve should remain    
closed throughout two-thirds or         
three-quarters of every two revolutions 
of the flywheel1 the greater part of the
 periphery of the cam is  circular1 or  
at the same distance from the axis at   
all points4    ,as has been mentioned   
before1 the cam serves only to lift the 
valve1  the return of the latter to its 
seat being obtained by the force from a 
spring that is coiled around the stem4  
,thus the spring holds the end of  the  
push rod at all times against the       
periphery of the cam4 ,this push  rod1  
in some instances1 is a small bar of    
special steel that slides in  guides of 
long-wearing bearing alloy4 ,the upper  
end of the push rod  is in contact with 

the lower end of the valve stem1 while  
its other  extremity is oftentimes      
designed in the form of a small steel   
roller  that thus serves to create a    
rolling contact with the periphery of   
the  cam4    ,in other designs1 the     
lower extremity of the push rod may be  
in the  form of a specially-hardened    
steel pin with a rounded end1 while     
still  a third type consists of a flat  
disc slightly offset on the end of  the 
push rod so that various points of its  
surface will come in contact  with the  
periphery of the cam and the wear will  
be evenly distributed4  ,whatever the   
particular design1 however1 the cam is  
well lubricated  and both it and the    
push rod are intended to last as long as
 any part  of the motor4    ,many motors
 are designed with one valve at the side
 and the other1  usually the intake1 in 
the head4 ,there are also many motors   
manufactured that have both the intake  
and the exhaust valves located  in the  
head1 in which case the valve pockets1  

or projections1 are  eliminated4 ,such  
valves may be operated by the same type 
of cams and  cam shaft as those used to 
open the valves at the side4 ,as the    
opening  of a valve located in the head 
is downward1 however1 the motion        
produced by the cam on the push rod must
 be reversed in direction4  ,this       
reversal of motion is obtained by means 
of a lever mounted at  its center and   
placed in contact with the upper        
extremity of the push  rod at its outer 
end4 ,the other end of this lever       
operates in contact  with the end of the
 valve stem1 and thus an upward push on 
the rod is  converted into a downward   
thrust on the stem4 ,this lever that    
reverses  the direction of the push rod 
motion is known as a rocker arm and is  
mounted in a yoke cast with the cylinder
 head4    ,inasmuch as a spring is used 
to keep the valve tightly closed when   
the cam is not lifting the latter1 it is
 the contact of the valve head  with its
 seat that must form the stop to the    

motion of the spring4 ,it  will be seen 
that the force of the spring is         
communicated through the  valve stem to 
the push rod1 and thence to the         
periphery of the cam when  the latter is
 in a position to lift the valve4 ,the  
push rod should not  be forced tightly  
against the periphery of the cam when   
the valve is  closed1 however1 for this 
would prevent perfect contact between   
the  valve and its seat4 ,consequently  
there should be a certain amount of     
play between the end of the push rod and
 valve stem so that it will  be certain 
that the head is forced against the seat
 with the full power  of the spring and 
without the cam serving as a stop4      
,on the other hand1 this play should not
 be too great1 for the cam and  push rod
 will then move an appreciable distance 
before the valve is  raised4 ,this will 
cause the opening of the valve to occur 
late and  will reduce the distance that 
the stem is raised1 thus restricting the
  size of the opening4 ,furthermore1 an 

undue amount of play between the  ends  
of the push rod and stem will result in 
a pound or hammer blow  between the two 
that is liable to wear the surfaces     
rapidly4    ,the happy medium that will 
give the best results may be obtained by
  properly setting the small valve      
tappets that are secured to the  end of 
the stems or push rods4 ,by turning the 
nut of the tappet in  one direction1 the
 length of the push rod will be reduced1
 while the  reverse operation will      
increase the length of the rod or stem4 
,this is  primarily intended for taking 
up any wear that may occur at the ends  
of  the push rod or valve stem4 ,in the 
case of engines having the valves in    
the head1 the long push rod of each     
valve should be so loose as to move     
perceptibly when shoved up and down by  
the thumb and finger4    ,when the      
rocker arm is pressed down against the  
valve stem1 the space  between the other
 end of the rocker arm and the push rod 
should be  sufficiently wide to admit a 

piece of tissue paper4 ,the same test   
may  be made in connection with valves  
located at the side1 after first        
ascertaining that the end of the short  
push rod is resting firmly  against the 
periphery of the cam4 ,the play will be 
apparent1 of course1  only when the     
valve is tightly closed1 and in order to
 make certain  that their cams are in   
the inactive position1 the piston should
 be  set at the beginning of the        
explosion stroke when testing the intake
  or exhaust valve4 ,this is at the     
point of ignition and is the time at    
which both valves should be tightly     
closed4    ,the cam shaft to which the  
cams that operate the valves are        
attached  is generally placed inside the
 crank case4 ,if the motor is of the    
,t-head type1 having valves on opposite 
sides of the cylinders1 the  cam shaft  
operating the exhaust valves will be    
found on one side of the  crank case1   
while that for opening the inlet valves 
will be located on  the other4 ,if the  

motor is of the ,l-head type1 all the   
cams will be  placed on the one shaft4  
,the cams are sometimes forged with     
their shaft  in a solid piece1 while in 
other designs they are keyed in place1  
but  whatever type is used1 the cams and
 their shaft may be considered as       
integral with each other4    ,the cam   
shafts are generally driven by a gear   
meshing with a smaller  one attached to 
the front end of the crank shaft of the 
motor1 which  forms one of the forward  
train of gears that are enclosed in an  
aluminum case4 ,if the cam shaft is     
driven at the same speed as is  the     
crank shaft of the motor1 it will be    
seen that the valves will  open once at 
every revolution of the flywheel4 ,in a 
four-cycle motor1  however1 the         
explosion and other events occur but    
once in each cylinder  for every two    
revolutions of the flywheel1 and        
consequently the cam  shaft must be     
driven at one-half the speed of the     
crank shaft4    ,to obtain the proper   

speed ratio1 each cam shaft is driven by
 a  two-to-one gear1 which means that   
the gear on the end of the crank  shaft 
has but one-half as many teeth as have  
those attached to the cam  shafts4      
,there is thus one revolution of each   
cam shaft gear for every  two of the    
crank shaft gear1 and consequently each 
cam shaft is driven  at the required    
half speed4    ,the cam shafts may be   
driven by a chain1 the links of which   
fit over  teeth cut on sprocket wheels1 
but there must always be a constant     
relation between the position of the cam
 shaft and that of the crank  shaft4    
,this constant relation is necessary in 
order that the valves  will open and    
close at the proper points during the   
travel of the  piston4 ,for example1 the
 exhaust valve should open toward the   
end of  the explosion stroke in order to
 allow the burned gases to be forced    
out1 and the cam for operating this     
valve should always be in the  lifting  
position at exactly the proper moment4  

,if the cam shaft is not positively     
driven1 this position may change and    
the exhaust valve might be opened at the
 beginning of the ignition  of the      
charge1 in which case the force of the  
explosion would be  wasted almost       
entirely4 ,on the other hand1 the inlet 
valve should  open at about the         
beginning of the suction stroke in order
 that the  fresh charge may be drawn in 
by the downward travel of the piston2   
it is evident that this cannot be opened
 at any other time without a  resulting 
loss in the power developed by the      
motor4    ,the proper timing of the     
action of the valves is consequently one
 of  the most important adjustments of a
 motor4 ,when the motor is assembled    
and tested at the factory1 the valves   
are properly timed and there  is no     
possibility that they will require      
further adjustment in this  respect     
until after the engine is taken down for
 the purpose of  cleaning or the renewal
 of a broken part4 ,if it should ever   

become  necessary to remove one of the  
cam shafts or any of the gears          
constituting the forward train1 the     
greatest care should be taken  to make  
certain that all are returned to exactly
 their original  position4 ,a difference
 of one tooth in the relative meshing of
 the  gears may result in a loss of     
fifty per cent4 of the power developed  
by  the motor4    ,absolute rules for   
the proper timing of the valves cannot  
be given  here1 for various motors are  
designed with slightly different        
positions at which the exhaust and inlet
 valves should be opened and  closed4 ,a
 cam shaft should never be removed1     
however1 without first  marking the     
intermeshing teeth of its driving gear  
and those of its  companions4 ,this may 
best be done by means of a small prick  
punch  which1 when tapped lightly with a
 hammer1 will make a permanent mark  at 
the desired point on the surface of the 
gear4 ,if the motor is of  the ,t-head  
type1 having its valves operated by two 

cam shafts1 care  should be taken to    
designate the right and left-hand gears 
so that  their positions will not be    
reversed if both have been removed at   
the  same time4    ,a safe method to    
pursue is to indicate the right-hand    
gear with one  punch mark1 while two    
should be used for the gear at the left4
 ,three  teeth should be marked on each 
pair of intermeshing gears4 ,that is1 a 
tooth on one gear should be marked1 and 
then each of the teeth between  which it
 meshes on the other gear4 ,the second  
cam shaft gear should be  marked before 
the motor is turned4    ,as has been    
stated1 the cams on many motors are     
forged integral with  their shafts1 and 
there is consequently no possibility of 
the removal  of one from the other4     
,those cams which are keyed to their    
shafts are  accurately and rigidly set  
and the keyways so cut that there is    
slight  chance of a mistake in returning
 a cam that has been removed4 ,it should
  seldom be necessary to remove a cam   

from its shaft1 however4    ,many motors
 are provided with timing marks on the  
flywheel to indicate  the positions of  
the latter at which the valves of the   
various  cylinders should open and      
close4 ,in connection with these marks a
  pointer attached to the crank case and
 indicating the top of the  flywheel is 
used4 ,when the  marked1 for example1 #d
  ,ex #j1 is under the pointer1 it      
indicates that the exhaust valve on the 
fourth cylinder should be about to open4
 ,if the motor is turned but  very      
little beyond this point1 a lifting     
should be felt at the proper  push rod  
or valve stem4    ,it is well to test   
the setting of the valves occasionally  
by means of  these marks1 for wear at   
the rocker arms1 the push rods1 the     
valve  stem1 or the cam travelers will  
result in unevenly-timed valves4 ,it    
should be remembered that it is the     
valve itself that should open  after the
 proper mark on the flywheel has been   
passed1 and that the  movement of a long

 push rod is not sufficient evidence    
that the valve  is beginning to leave   
its seat4 ,there may be so great an     
amount of lost  motion between the push 
rod1 cam1 rocker arm1 and valve stem    
that the  flywheel may be turned several
 degrees beyond the proper point before 
this play will be taken up and the valve
 itself will begin to move4    ,although
 the timing of a motor may be given in  
inches of piston travel  beyond a       
certain dead center1 at which point an  
exhaust or inlet valve  should open or  
close1 it is generally expressed in     
degrees of flywheel  revolution4        
,suppose1 for example1 it is said that  
the inlet valve  should open ten degrees
 after the beginning of the suction     
stroke4 ,this  would indicate that the  
flywheel should be turned through an arc
 of ten  degrees from the point at which
 the piston is at its upper dead center 
before the inlet valve for that         
particular cylinder should begin to     
open4 ,expressed in terms of flywheel   

revolution1 the total travel of  the    
piston during each stroke is #ahj       
degrees1 and as in the proximity  of its
 dead centers the piston moves but a    
short distance in comparison  with the  
size of the arc through which the       
flywheel swings1 valves may  be set very
 accurately by this method4    ,not all 
cam shafts for operating the valves are 
located in the crank  case4 ,on several 
designs of motors the cam shaft extends 
along the top  of the cylinders and is  
driven by a vertical shaft and two sets 
of  bevel gears4 ,on such motors both   
inlet and exhaust valves are located  in
 the cylinder heads1 and owing to the   
proximity of the cam shaft1 but  short  
push rods and valve stems are needed4   
,the valves are sometimes  operated by  
means of a bell crank or rocker arm that
 acts directly  against the cam surface 
and end of the valve stem4    ,on some  
designs a double cam is used which      
serves to operate both the  inlet and   
exhaust valves of the cylinder4 ,the    

bearings and cams of such  a shaft are  
generally enclosed in oil and dustproof 
casing screwed to  the top of the       
cylinders4 ,such a cam shaft should     
never be dismounted  without first      
marking intermeshing teeth of all spur  
and bevel gears  that are concerned in  
its operation4    ,all poppet valves    
must be accessible and readily removable
 for the  purpose of cleaning and       
grinding the contact surfaces of the    
head and  seat4 ,the pockets in which   
the valves placed at the side of a      
cylinder  are located are generally     
provided with large screw plugs at the  
top4  ,such a plug may be removed with a
 heavy wrench1 and as the opening  which
 it fills is larger than the head of the
 valve1 the latter may be  removed after
 first loosening the spiral spring      
surrounding its stem4  ,it is not       
necessary to remove the valve entirely  
from its pocket in  order to grind its  
surfaces1 but the pin holding the spring
 stop in  place must be withdrawn so    

that the tension of the spring on the   
valve  will not be so great as to       
prevent the latter from being lifted to 
permit the introduction of the abrasive 
and turning the head with the  grinding 
tool4    ,valves located in the head of 
the cylinder must be removed entirely   
before their surfaces can be ground4    
,this1 however1 is not a difficult      
operation1 as the valve and its seat are
 generally placed in a  removable cage  
that either screws in place or is held  
firmly in  position by means of a clamp 
or like device4 ,inasmuch as the seat is
  contained in this removable cage in   
which the valve operates1 the  grinding 
may be done at a work bench or on the   
bed of any convenient  tool1            
independently of the location of the    
motor4    ,if a valve seems sluggish in 
its action at high speeds of the motor1 
it  is possible that its spring has     
become somewhat weakened4 ,these springs
  are designed to be exceedingly stiff  
and heavy1 some of them requiring  a    

pressure of two hundred and fifty pounds
 to compress the coils one  inch4 ,with 
such a spring1 a special tool is        
required to compress it  sufficiently to
 enable the valve to be removed4 ,a     
spiral spring that  has become weakened 
may sometimes be strengthened by        
stretching1 but  it is not to be        
supposed that this would be of great    
avail in the case  of a spring as heavy 
as those used on some valves4 ,if1      
however1 a flat  tool is introduced     
between the various coils and each is   
separated  slightly so that the ultimate
 length of the entire spring is greater 
than it was formerly1 it will exert a   
more powerful force on the valve  when  
it is returned to its place surrounding 
the stem4    ,stiffening the spring1    
however1 will be of but little help if  
the stem  or push rod is tight in the   
guides through which it slides4 ,these  
guides are often made of a special      
bearing bronze and are designed to      
withstand a large amount of wear1 but   

the friction surfaces must be           
lubricated if satisfactory service is to
 be obtained4 ,the lower guide  is      
generally lubricated by the oil from the
 cams1 while the guide  near the valve  
may receive its oil from the engine     
cylinder4 ,it is  not necessary that    
these guides shall be packed or that    
they shall be  particularly tight1 as   
they are not called upon to retain any  
gas or  air pressure1 but they must hold
 the stem and rod sufficiently rigid to 
prevent any perceptible side motion and 
thus cause imperfect seating  of the    
valve4 ,in replacing valve stems and    
push rods1 it should be  made certain   
that each works freely in its guide     
before the spring is  installed4 ,if    
there is a slight tendency for the guide
 to grip the rod  or stem1 the latter   
should be smoothed with emery paper at  
the point  at which it comes in contact 
with the guide and plenty of oil applied
  until the surfaces are well worked    
down4 ,as the distance that the  rods   

and stems travel through the guides is  
comparatively short1 the  wear is slight
 and only a small amount of lubricant is
 needed1 provided  the rubbing surfaces 
are smooth and well-fitted to each      
other4    ,the mechanism of a sleeve    
valve motor is slightly different from  
that  of the poppet valve type4 ,each   
sleeve is operated by a connecting  rod 
and eccentric mounted on a shaft driven 
by a chain or gears from  the crank     
shaft of the motor4 ,the eccentric      
replaces the cams of the  poppet valve  
motor1 and as it must maintain a certain
 relation with the  position of the     
piston in order that the operation of   
the valves shall  be timed correctly1   
the same care must be observed in       
replacing the  eccentric shaft with the 
proper teeth of the sprocket or gear in 
mesh  as has already been described in  
connection with the cam shaft of the    
poppet valve motor4          ,,chapter  
,,iii    ,,bearings      ,in the general
 meaning of the term1 a bearing is any  

part that carries  weight or pressure   
and at the same time rubs over another  
surface4  ,according to this definition1
 the portion of the cylinder walls      
traversed by the pistons are bearings1  
and that is in reality the case1  but   
the term has come to be applied more    
specifically to the part of  the machine
 in which another part revolves1 either 
continuously or  intermittently4 ,thus  
the portions of the crank shaft on which
 it is  supported and the parts of metal
 in which they revolve combine to form  
the crank shaft bearings4 ,the shaft or 
stud on which a gear or wheel is        
mounted and on which it revolves is the 
bearing of that gear or wheel4          
,although they are concealed1 as some   
six-cylinder motors may be  provided    
with as many as three dozen1 or more1   
bearings--if we consider  those on which
 the cam1 pump1 and magneto shafts and  
the gears are  mounted--but what        
descriptions1 rules1 and precautions    
apply to all  hold true in the largest  

sense when the crank shaft1 connecting  
rod1  and wrist pin bearings only are   
considered4 ,it is on this latter class 
that the greatest wear of the motor is  
concentrated1 and the owner who         
understands and inspects these need fear
 no trouble from the cam shaft  and gear
 bearings4    ,the expert will judge of 
the condition of a motor by the wear    
that has  occurred in the bearings      
rather than by any exhibition of        
temporary  power that it may develop in 
a short test1 and it is for this reason 
that the general public runs a risk     
whenever it buys a second-hand  car that
 has not been thoroughly overhauled by a
 reputable factory or  inspected by a   
competent engineer4 ,the bearings are in
 reality the  vitals of the motor1 and  
when these are worn beyond the point of 
easy  adjustment or renewal1 the repairs
 necessary to place the machine in  good
 condition would oftentimes cost more   
than the entire engine is  worth4 ,but  
even in a badly-worn motor1 the bearings

 may be taken up  and doctored so that1 
for a while at least1 the engine will   
seem to  run perfectly and develop its  
full power4 ,this will not be for long1 
however1 and soon the motor will begin  
to pound1 knock1 and rattle  until an   
examination will bring to light the true
 condition of the  bearings4    ,in no  
machine are the bearings subjected to   
more severe usage than in  the          
automobile motor4 ,in order that the    
motor car power plant shall  be light in
 weight and occupy but a small amount of
 space1 the power  must be transmitted  
at high speeds4 ,in many an automobile  
motor1 the  pressure imparted to a      
single bearing during a certain portion 
of its  revolution may frequently be    
well over two tons1 and in this same    
bearing1 the speed of rubbing may       
approach eight or nine hundred feet  per
 minute4 ,in other words1 at normal     
speeds of the motor1 about a  sixth of a
 mile of steel surface will rub over a  
certain point in each  crank shaft      

bearing during every minute that the    
engine is running4    ,when properly    
lubricated1 an iron or steel shaft will 
run in almost  any kind of a metal      
bearing that is sufficiently strong to  
carry the  weights and pressures imposed
 upon the shaft4 ,the friction generated
  between two different metals that rub 
against each other1 however1  varies    
according to the composition of those   
metals1 and consequently  it is         
advisable to employ some material for a 
bearing that will offer  a minimum      
resistance to the turning of the shaft4 
,friction must be  reduced between all  
moving surfaces in order that the       
mechanical  efficiency of the machine   
shall be high1 and it is in the bearings
 that  a large amount of power may be   
absorbed4    ,but even between the      
best-lubricated surfaces1 employing the 
most  efficient metal as a bearing1 some
 wear is bound to occur4 ,the crank     
shaft of a four- or a six-cylinder motor
 is forged or sawed from  one piece of  

steel1 and with the accurate machining1 
finishing1 and  grinding to which it is 
subjected1 it becomes an expensive part 
of  the engine4 ,consequently it is     
advisable that the wear of bearings  of 
such parts shall be restricted to the   
boxes or surrounding  stationary metal  
in which the shaft revolves at these    
points4 ,in order  that all wear shall  
occur here1 rather than in the shaft1   
the boxes  are made of or lined with a  
softer metal4 ,if the crank shaft is of 
hard steel1 the bearing metal may be of 
brass or bronze1 but it has  been found 
that babbitt metals give the most       
satisfactory service for  such          
conditions--particularly as a           
sufficiently hard crank shaft is        
difficult to produce commercially4      
,not only is a babbitt metal softer than
 the steel of the shaft and             
consequently receives practically all   
the wear of the bearing1 but it  has the
 added advantage of melting at          
comparatively low temperatures4  ,at    

first thought1 this may seem like a     
doubtful advantage1 but in case  of a   
failure of the oil supply to that       
bearing1 this characteristic may  be the
 means of saving the crank shaft1 and   
possibly the crank case1  cylinders1 and
 connecting rods1 from rack and ruin4   
,the purpose of lubrication is to reduce
 friction between the two  surfaces in  
contact4 ,friction generates heat1 and  
consequently the  temperature of a      
bearing to which a sufficient supply of 
oil is not  delivered will be raised to 
a very high point4 ,this high           
temperature  will cause both parts of   
the bearing to expand1 with the result  
that  the fit becomes very tight and the
 shaft binds or seizes in its box4      
,this is the familiar hot box1 so often 
the bane of railroad men1 and  if the   
shaft is still run under these          
conditions1 the bearing material  will  
be torn out and the surface of the      
shaft1 axle1 or whatever the  revolving 
portion happens to be1 will be cut and  

abraded1 oftentimes  beyond the         
possibility of repair4 ,it is such      
accidents as these that  are prevented  
by the use of an easily-melted babbitt  
metal4    ,if the oil supply becomes    
insufficient so that the temperature of 
the  bearing is raised above a certain  
point1 the babbitt metal will be  melted
 and will run out of its container      
before any damage can be done  to the   
shaft4 ,efficient running cannot1 of    
course1 be obtained with the  bearing   
burned out in this manner1 but the      
babbitt is quickly and  easily renewed  
and serves as a sort of fusible safety  
valve that saves  many an expensive     
crank shaft replacement4    ,babbitt    
metals may be of various compositions   
and proportions and many  contain lead1 
but those which have been found to give 
the best results  for use on the crank  
shafts of automobile motors are composed
 only of  tin1 antimony1 and copper4 ,if
 lead is used at all for this purpose1  
it should not appear in proportions     

above one per cent of the total         
composition4 ,inasmuch as a babbitt     
metal will fuse at a comparatively  low 
temperature and is much softer than     
steel1 it is obvious that such  a       
material will not withstand heavy       
pressures unless reinforced and is      
unsuited for structural purposes4       
,consequently the babbitt is placed  in 
the bearing box in the form of a thin   
lining within which the shaft  revolves4
    ,when the shaft is lined up in the  
box1 the hot babbitt metal may be       
poured in until the space is entirely   
filled4 ,when the babbitt cools1  the   
shaft may be turned1 and when lubricant 
has been introduced in  the oil grooves 
which should have been provided for the 
purpose1 the  new bearing will be ready 
for use4 ,it is not to be expected that 
the  majority of motor car owners will  
rebabbitt the crank shaft bearings      
themselves1 but it is necessary to      
understand the general principles of    
such bearing design in order to inspect 

the motor intelligently and to          
determine upon the repairs needed4      
,the above method of renewing burned out
 bearings applies to babbitts  in       
general1 but the severe usage that      
automobile engine crank shaft and       
connecting rod bearings are called upon 
to withstand necessitates the  exercise 
of a certain amount of additional care4 
,it is necessary that  the box shall fit
 the shaft perfectly1 so that there can 
be no play1  and yet the shaft must be  
allowed to turn easily within its       
surrounding  babbitt metal4    ,as was  
stated above1 the shaft may be easily   
loosened from the babbitt  metal after  
the latter has cooled1 and this would   
form a satisfactory  type of bearing    
were it not advisable that some means be
 supplied by  which the wear could be   
taken up without renewing the entire    
babbitt  lining4 ,the bearing boxes of  
the crank shaft are each made in two    
halves1 the lower portion being cast    
integral with the crank case1  while the

 upper half is in the form of a separate
 cap that may be held  in place by two  
or four bolts4 ,in this case1 it is     
necessary that  the boxes shall be in   
two sections1 for the shape of the crank
 shaft  prevents it from being slid into
 place lengthwise1 and consequently it  
must be placed on its bearing from the  
top4 ,in some designs of motors  the    
bearing caps form the lower half of the 
box1 but as in this case  the base of   
the motor must be inverted in order to  
remove the crank  shaft1 the caps will  
still be considered as the top halves of
 the  boxes4    ,there may be dove-tail 
grooves cut in the inside of the halves 
of the  boxes to retain the babbitt     
metal after it has been poured in place4
  ,consequently1 in order to remove the 
cap after renewing the babbitt  lining1 
the babbitt metal must be cut in two at 
the joint between the  two halves of the
 box4 ,the two halves of the box1       
instead of fitting  closely together1   
are separated by thin strips of copper  

or fiber known  as shims that serve to  
relieve the shaft from the pressure of  
the  bolts when the bearing cap is      
screwed in place4 ,in other words1 the  
two halves of the box must be held      
tightly in place by means of the  bolts 
and nuts1 but none of this pressure     
should rest on the revolving  shaft1 as 
this would bind it and prevent it from  
turning easily4  ,consequently by       
building up the space between the two   
halves with  these thin shims the proper
 adjustment may be obtained4    ,these  
shims provide the method of taking up   
the wear in the babbitt  that will      
eventually result4 ,by loosening the box
 retaining bolts and  removing the      
required number of shims1 the halves of 
the box will be  brought closer         
together4 ,when the bearing cap is      
screwed securely in  place1 the shaft   
should be able to revolve freely without
 binding1 and  yet the fit should be    
sufficiently tight to prevent any play  
at right  angles to the length of the   

shaft4    ,the pressure of a shaft      
should not be concentrated in one place1
 but  should be distributed over as     
large a surface of the babbitt metal as 
is possible4 ,a few years ago1 when     
renewing or repairing a bearing1 it  was
 considered sufficient to pour in the   
molten metal or to remove the  proper   
number of shims--and the bearing was    
then said to be ready for  its work4    
,but even though no play was apparent1  
it was possible that  the shaft rested  
on only a few portions of the bearing   
surface2 and  the increased attention   
that is now paid to the details of      
automobile  construction is no better   
exemplified than in the fact that nearly
  all bearings are scraped in4 ,this    
operation is simple and consists  merely
 in removing any slight excess babbitt  
metal so that the lining  fits the shaft
 throughout its entire length and       
circumference4 ,the  babbitt is         
sufficiently soft to enable it to be    
peeled or scraped with  a sharp tool    

provided for the purpose1 and no great  
degree of skill is  necessary in        
obtaining the required fit4    ,in order
 to determine at exactly what portions  
of the babbitt lining  the pressure is  
too great1 a dye or paint known as      
blueing is used4  ,the bearing portion  
of the crank shaft is painted with this1
 and the  cap is then screwed in place4 
,if the crank shaft is then turned and  
the  cap removed1 it will be found that 
the blueing has been transferred  from  
the bearing to the portions of the      
babbitt metal on which the  pressure is 
the greatest4 ,these portions should    
then be shaved with the  tool mentioned 
above1 and the same test repeated4 ,as  
the excess metal  is removed1 it will be
 found that the blueing gradually is    
deposited  over a larger area of the    
babbitt1 but it is not to be supposed   
that  the fit can be made so perfect    
that the color will be distributed      
evenly over the entire surface4 ,care   
should be taken to screw the  bearing   

cap onto the shims as tightly as        
possible each time the blueing  test is 
to be made4    ,there is nothing that   
will heat a bearing so quickly as a poor
  alignment of the shaft supported by   
it4 ,for this reason gasoline engine    
crank shafts are made exceptionally     
strong and heavy1 especially those  that
 are supported only at their            
extremities1 or at these points and in  
the center of their length4 ,a shaft    
that is bent or twisted to even the     
slightest degree will soon burn out all 
of its bearings1 regardless  of the     
amount of oil that may be fed to them4  
,this is because of the  unequal        
pressures on the different sides of the 
bearing that allow no  room for the     
admission of the film of oil or other   
lubricant that is  necessary in all     
cases to prevent a hot box4    ,on the  
other hand1 the bearings must all be in 
perfect alignment1 for  to set one      
slightly off would produce the same     
result as though the  shaft were bent4  

,it will be seen that the use of babbitt
 produces a  self-aligning bearing1 for 
the straight shaft may be set in its    
proper position and the molten metal    
poured around the interior of the       
boxes4    ,as it is highly important    
that the cap screws or nuts holding the 
bearing cap in place should remain set  
as tightly as possible1  precautions    
must be taken to prevent any of these   
from working loose4  ,this may be done  
by means of a cotter pin that passes    
through a hole in  each bolt and through
 a pair of corresponding notches cut in 
the top of  opposite faces of the nut4  
,a notch is generally cut in the top of 
each  face of the nut in order that the 
latter may be held securely in place  in
 any position4 ,a continuous wire       
passing through all of the bolts and    
nuts is sometimes used instead of the   
individual cotter pins4    ,many modern 
automobile motors are designed with the 
crank shaft running  in ball bearings4  
,the type generally used consists of a  

row of balls  set between the inner and 
outer edges of two concentric rings4    
,the  inside of the outer and the       
outside of the inner ring are grooved1  
constituting the ball race which forms  
the surface upon which the  balls roll  
and which1 at the same time1 serves to  
hold them in place4  ,each ball of the  
same bearing must be made of exactly the
 same size as  its companions--or at    
least within one or two ten-thousandths 
of an  inch--and each one must be large 
enough and of sufficient strength to    
withstand1 by itself1 the entire        
pressure in that bearing4 ,the inner    
ring slips over the bearing portion of  
the shaft with a comparatively  tight   
fit1 while the outer ring remains       
stationary in its bed in the  crank     
case4    ,the inner ring turns with the 
shaft1 thus causing the balls to roll in
  their race4 ,each ball rolls about its
 own axis1 and the entire series        
describes a circular motion in the same 
direction as that taken by  the shaft1  

but considerably slower4 ,consequently  
there is no rubbing  in such a bearing1 
all the motion being of the rolling     
type1 and as  this reduces friction to a
 minimum1 the balls may be run without  
oil1  although lubrication of the proper
 kind would certainly not harm the      
bearing4 ,ball bearings are adapted only
 for a two-bearing crank shaft1  for    
inasmuch as the rings must be slipped   
over the shaft1 it would be  manifestly 
impossible to provide a ball bearing in 
the center1 or in  any other portion    
beyond a crank4    ,next in importance  
to the main bearings of a crank shaft   
are those by  which the connecting rods 
communicate their motion to the cranks4 
,these  are known as the crank pin      
bearings or the big end of the          
connecting  rod bearings4 ,but inasmuch 
as the upper1 or smaller1 end of the    
connecting rods are termed the wrist-pin
 bearings1 the other end may be  called 
simply the connecting rod bearing4      
,the connecting rod bearings are similar

 to the main bearings described  in the 
foregoing pages and are renewed and     
adjusted in the same manner4  ,it is    
probable1 however1 that these receive a 
greater amount of wear  than do the main
 bearings1 inasmuch as the former obtain
 the direct  impact of the force of each
 explosion4 ,furthermore1 the box of the
  connecting rod bearing describes a    
complete circle with each revolution  of
 the crank shaft1 in addition to the    
internal rotation of the  crank1 while  
an alternate push and pull is delivered 
to it by the  connecting rod on its     
various strokes4    ,consequently it is 
the connecting rod bearings that will   
become loose  and require taking up     
before any attention need be bestowed on
 the  main bearings4 ,the wear will     
increase in the connecting rod bearing  
as  the play becomes greater1 and if    
matters are not remedied1 the box may   
eventually be broken1 with the result   
that the end of the connecting  rod thus
 freed will start on the rampage and    

will punch several  pieces out of the   
bottom of the crank case4    ,brass or  
bronze bearings may be used at the big  
end of the connecting  rods1 but the    
large majority of motor car engines are 
provided with  babbitted bearings at    
these points4 ,it is especially         
necessary that  these bearings should be
 scraped to a perfect fit and that the  
shims  should be adjusted properly so   
that no side play will be apparent  when
 the connecting rod is moved            
transversely to the length of the  crank
 shaft4 ,when renewing the babbitts of  
connecting rod bearings  care should be 
taken to allow the connecting rod to    
swing free before  the molten metal is  
poured in4 ,if this is not done1 the    
connecting  rod may be forced slightly  
to one side or the other and will be    
held  permanently in this position when 
the babbitt cools4 ,this will induce  a 
slight side thrust in the connecting    
rod1 which will be communicated  to the 
piston1 with the result that the side of

 the latter and of the  portion of the  
cylinder wall against which it moves    
will be scored and  worn unduly4        
,inasmuch as the connecting rod bearings
 are subjected to such a variety  of    
strains1 and as looseness at these      
points will result in serious  wear1 it 
is doubly necessary that the nuts and   
bolts holding the  bearing caps in place
 should be securely wired or held       
tightly by means  of the                
previously-mentioned cotter pins4 ,it is
 evident that the base of  the large end
 of the connecting rod forms the upper  
half of the bearing  box1 while the cap 
constitutes the lower end and is        
attached from the  bottom4    ,the      
connecting rod bearings on some motors  
are hinged at one side so  that the cap 
may be turned away from the crank shaft 
when it is desired  to remove the       
connecting rod4 ,in this case the hinge 
replaces the one  or two bolts or nuts  
on one side of the box and is held in   
the proper  position by those on the    

other side4 ,while it may be easier to  
adjust  a bearing provided with such a  
cap1 the results obtained can hardly  be
 expected to be as satisfactory for     
high-grade service1 as is the  case when
 the shims may be used on both sides of 
the two halves of the  bearing4    ,the 
wrist-pin bearing is located at the     
upper1 or small1 end of each  connecting
 rod1 and1 although it also carries the 
full force of each  explosion1 it is not
 subjected to as great wear as is the   
bearing at  the other end of the        
connecting rod4 ,the reason for this is 
that this  bearing does not revolve and 
its friction surface is reduced to the  
comparatively small arc through which   
the connecting rod swings4 ,wear  can   
occur here1 however1 and because this   
bearing is more inaccessible  than is   
the crank shaft or connecting rod       
bearing1 trouble at the wrist  pin is   
often overlooked4    ,the wrist pin can 
only be reached by the removal of the   
piston and  connecting rod4 ,in the     

majority of designs the wrist pin is    
placed  in the sides of the piston and  
is held stationary by small keys or  by 
set screws4 ,in this case1 the bearing  
surface is formed by the  wrist pin and 
the small end of the connecting rod1 at 
which point the  greatest wear occurs4  
,this bearing is never babbitted1 but in
 order to  reduce the wear on the wrist 
pin--which is generally made of hardened
  steel--the circular opening in the    
upper end of the connecting rod is      
lined with a bronze or brass bushing    
that forms a bearing fit over  the wrist
 pin4 ,it is this lining1 or bushing1   
that will wear rather  than the hardened
 steel wrist pin1 but as the former is  
easily removed  and is not expensive to 
replace1 the renewal of this bearing is 
a  comparatively simple matter4    ,in  
other types of wrist pin bearings1 the  
pin is held stationary in the           
connecting rod opening and turns with it
 as the connecting rod swings  through  
its arc on each stroke of the piston4   

,with such a design1 the  bearing       
surface is formed by each end of the    
wrist pin and the openings  in the sides
 of the piston walls in which the wrist 
pin rests4 ,in order  to form an        
easily-replaced bearing surface1 these  
openings in the  piston walls are lined 
with brass or bronze bushings that      
receive the  major part of the wear1 as 
has been described in connection with   
the  bushings fitted to the opening at  
the small end of the connecting rod4    
,there is nothing complicated or        
mysterious connected with the renewal   
or repair of bearings1 but the man who  
makes such replacements or  adjustments 
must be an accurate and careful worker1 
and while he  need not be a born        
machinist1 he must at least possess the 
knack  of handling tools properly4 ,and 
he must1 above all1 realize that  the   
designers and manufacturers of his motor
 have been dealing in  measurements of  
the thousandth part of an inch and that 
too great care  cannot be taken in the  

repair of bearings to obtain a perfect  
fit4    ,if he is renewing a connecting 
rod or a wrist pin bearing1 he must     
also remember that the piston has       
formerly been traveling over a  certain 
area of cylinder surface that has not   
varied in length the  ten-thousandth    
part of an inch between one stroke and  
the next4  ,consequently1 the babbitts  
or bushings should be so replaced that  
the  piston shall occupy the same       
position relative to the cylinder walls 
at  the top and bottom of its stroke    
that it did formerly4 ,in other words1  
by varying the thickness of the top of  
the babbitt he is replacing1 he  may    
change the center of the bearing so that
 the piston will start  on its upward   
stroke from a different point than was  
previously the  case4 ,thus1 while the  
length of travel of the piston will be  
the same1  it will traverse a slightly  
different portion of the cylinder walls 
under the new conditions1 and this will 
have the effect of changing the         

compression and1 possibly1 of wearing   
the piston and rings unduly4            
,,chapter ,,iv    ,,the ,,ignition      
,,system      ,it was the application of
 the electric current to the ignition   
system  of the gasoline engine that     
first enabled these new forms of power  
plants to be designed with sufficient   
compactness and to possess  enough      
flexibility to render their use         
practical on self-propelled  vehicles4  
,without the electric ignition system1  
the speed and power of  the vehicle     
could not well be controlled1 and the   
explosions would be  uncertain and      
irregular1 at best4    ,those of us who 
are familiar with the electric gas      
lighters that  were in popular use a few
 years ago are furnished with a         
convincing  demonstration of the        
operation of the first electric ignition
 systems4  ,by pulling a chain1 a wire1 
or arm was rubbed across a metal point  
until the contact thus formed was       
suddenly broken4 ,this arm and the      

stationary point formed the two         
terminals of an electric circuit1 which 
caused a flash of blue flame when the   
contact was broken as the one  was wiped
 across the other4 ,the flame thus      
formed at the instant the  contact was  
broken contained sufficient heat to     
ignite the gas escaping  from the burner
 to which the device was attached4      
,sparks will be formed in the same      
manner if we hold two wires1  connected 
to the opposite poles of a set of       
batteries1 in both hands  and wipe the  
bare ends across each other4 ,if an     
arrangement producing  this effect is   
introduced into the gas engine cylinder 
at the portion  in which the charge is  
compressed1 the flash resulting when the
  terminals are separated will serve to 
ignite the explosive mixture4  ,the     
movable terminal is connected to a rod  
which passes through the  cylinder walls
 and is attached to a mechanism actuated
 by a cam  revolved by the engine4 ,this
 mechanism is termed the make-and-break 

ignition system for the reason that     
contact of these terminals is           
alternately made and broken to produce  
the flash of electricity that  explodes 
the surrounding charge4    ,in order to 
produce a flash of sufficient size when 
the contact is  broken1 the nature of   
the current1 obtained from the dry cells
 or  storage battery is changed somewhat
 by conducting it through a coil of     
wire surrounding a bundle of bare copper
 wires4 ,this is known as a  spark coil1
 and while it is generally used with    
battery ignition of the  make-and-break 
type1 magnetos may be designed which    
produce the proper  kind of current     
direct1 without the aid of the coil4    
,an ordinary set of six dry cells1      
connected in series--or like with       
unlike poles--will produce a current of 
between twenty and twenty-five  amperes 
at a pressure of about nine             
volts--assuming each battery1 when  new1
 to deliver twenty-five amperes at a    
pressure of one and one-half  volts4    

,the series wiring gives the entire set 
the combined voltage  of all with the   
average amperage of one4 ,for the       
benefit of those who  have forgotten    
their elementary physics1 let it be     
remembered that the  ampere is the      
measure of current amount1 or flow1     
while the voltage  is concerned only    
with the pressure of the current4 ,by   
the use of  various arrangements of     
windings of wires1 the voltage may be   
raised  with a corresponding decrease in
 the amperage--and vice versa4 ,thus1 if
  a coil is used that doubles the       
original number of amperes produced by  
the battery1 the voltage will be halved4
    ,the make-and-break type of ignition
 has been used successfully for many    
years1 but with the perfection of the   
magneto1 it has been largely            
supplanted1 in automobile practice1 at  
least1 by the jump spark1 or            
high-tension system4 ,because of the    
fact that the latter system is  less    
expensive to construct and is highly    

efficient1 it will be found  also on the
 majority of the older cars not equipped
 with a magneto4    ,it was found1 after
 the general adoption of the            
make-and-break  ignition system1 that a 
flame was not necessary for the         
combustion of  a properly-mixed charge  
in the engine cylinder4 ,in fact1 a tiny
 spark1  scarcely one-sixteenth of an   
inch long and no larger around than a   
pin1 was discovered to be sufficient to 
produce the ignition of the  charge4    
,although1 of small volume1 such a spark
 generates intense heat1  and it is upon
 this quality1 rather than upon area1   
that the charge  depends for its        
ignition--although it is claimed that a 
large flame  will produce more complete1
 rapid1 and consequently more efficient1
  combustion4 ,but the jump spark       
possesses the advantage of requiring no 
moving parts projecting through the     
cylinder walls into the combustion      
chamber1 and its greater simplicity over
 that of the make-and-break  system has 

resulted in its almost universal        
adoption by automobile  manufacturers4  
,it has been stated in a preceding      
paragraph that the voltage produced  by 
the average battery set will not exceed 
nine or ten1 and even the  pressure     
generated by the ordinary magneto is not
 greater than this4  ,but air is not a  
good conductor of electricity and forms 
a very high  resistance to the passage  
of a current4 ,it is only when the high 
resistance of an air gap is encountered 
in its circuit1 however1 that  a spark  
will be formed by the current1 and      
consequently the form  of electricity   
used in this system must have           
resistance-overcoming  properties4 ,but 
it is only by raising the voltage of the
 current that  even a short air gap can 
be bridged by the spark4 ,in fact1 a    
pressure  of somewhat over fifty        
thousand volts is required to produce a 
spark  less than an inch long in the    
air4    ,although only called upon to   
jump a gap about a sixteenth of an inch 

across1 the ordinary high-tension       
current is capable of bridging a  space 
eight or ten times this width in order  
that ample pressure will  always be     
assured for the formation of the spark4 
,furthermore1 the  warm gases in which  
the spark is formed in the cylinder     
increase the  resistance ordinarily     
encountered and it is consequently      
necessary to  raise the voltage above   
the amount that would be needed were the
 plug  exposed to the open air4         
,these conditions make advisable a      
pressure of from twelve thousand to     
thirty thousand volts in the ordinary   
jump spark system1 and it is  from this 
voltage that the term high tension is   
obtained4 ,the nine  or ten volts       
delivered by the batteries are          
transformed to this larger  amount by   
means of an induction coil--or what is  
more generally termed  merely the coil4 
,this is in reality a step-up           
transformer1 since  it transforms the   
current from one of low voltage to      

another of two or  three thousand times 
its original pressure4    ,this         
transformer consists of two coils of    
wire1 one surrounding the  other4 ,the  
inner coil is composed of a             
comparatively few number of  turns of   
rather coarse wire wound around a soft  
iron core1 and is  termed the primary   
winding1 since the current from the     
batteries is  led directly through it4  
,the outer coil is composed of many     
turns of a  very fine wire1 all of which
 are thoroughly insulated from each     
other  and from the inner winding4 ,this
 outer coil is termed the secondary     
winding and is the one from which the   
high-tension1 or transformed1  current  
is taken4    ,this secondary current is 
induced from the primary winding through
  which the battery current passes and  
possesses a voltage that has  increased 
over its original amount in the same    
proportion that the  number of turns in 
the secondary winding bears to those in 
the  primary4 ,therefore1 if the        

original battery voltage is ten and     
there  are a thousand times as many     
turns in the secondary winding as in the
  primary1 the resulting high-tension   
current will have a pressure of ten     
thousand volts4    ,the principle of the
 coil is dependent entirely upon that   
peculiar  electric property known as    
induction4 ,around every wire through   
which  an electric current passes are   
invisible lines of force similar  to    
those that emanate from an              
electro-magnet4 ,these lines of force   
surround the wire throughout its length1
 and arrange themselves in a  spiral    
formation4 ,insulation has no effect on 
these lines of force1  and they may be  
collected from wires which are separated
 from each  other by several thicknesses
 of current-confining material4 ,it is1 
of  course1 necessary to use insulated  
wires in the construction of these      
coils1 for otherwise the current would  
merely pass to adjoining turns  and     
would not travel the entire length of   

the winding--and therefore as  great a  
number of lines could not be collected4 
,if an additional layer or layers of    
wire is wound around the first  series  
of turns1 the lines of force will be    
collected1 or induced1  by this second  
coil1 and will constitute the secondary 
current4 ,the  induction effect is      
greatly increased if the primary current
 is allowed  to accumulate1 or pile up1 
and discharge1 alternately1 for this    
surging of the current creates a sort of
 overflow from the original  containing 
wires4    ,ohm's ,law1 which states that
 the number of amperes in an electric   
circuit is equal to the voltage divided 
by the number of ohms of  resistance    
encountered1 shows that the current will
 be changed by its  passage through the 
primary winding4 ,the induced current is
 further  changed1 and when collected by
 the secondary winding and sent through 
its long coils1 we have the high-tension
 circuit mentioned in the  preceding    
paragraph4    ,if the reader remembers  

that it is but one hundred and ten volts
 that  is used to operate our electric  
lights and that five hundred will run a 
trolley car1 he may wonder why it is not
 dangerous to handle as great  a        
pressure as the thirty thousand volts   
that are used in connection  with the   
ignition system of a motor car4 ,but it 
is the combination  of great voltage    
with high amperage that is dangerous1   
and if it is  remembered that1 as the   
former is increased1 the latter is      
reduced  correspondingly1 it will be    
realized that the ordinary high-tension 
ignition current possesses a quantity1  
or flow1 of scarcely one  one-hundredth 
of an ampere4    ,if we liken the       
electric current to a flow of water in a
 pipe1 we have  the amperes             
corresponding to the quantity of the    
flow1 or the number  of gallons that    
will be delivered at the outlet in a    
given time4  ,continuing this analogy1  
the voltage of the electric current will
 be  the pressure1 or head in the water 

system1 and the current from the        
batteries before the coil is reached    
will correspond to a moderate  flow of  
water at a comparatively low pressure4  
,after the coil has  transformed the    
current to the high voltage1 we have the
 conditions  of a very small opening in 
the water pipe containing a tremendous  
pressure4 ,such a stream will possess   
but small flow1 but its high  pressure  
will enable it to be squirted to a far  
greater distance than  would be the case
 were its volume larger and its head    
less4 ,although  the pressure is high1  
its quantity is so low that the stream  
can do but  little damage and would     
scarcely more than tickle the flesh of a
 person  against whom it is directed4   
,thus it is with the ignition current4  
,it can tickle1 rather  viciously1      
sometimes1 as many persons will aver1   
but the amount  of electricity involved 
is so slight as to render the high      
pressure  harmless4 ,nevertheless1 it is
 well to avoid allowing the fingers or  

the  arm to become a part of the        
high-tension circuit1 for the result may
 be  startling as well as annoying4     
,but in order that the high voltage     
shall be induced in the secondary  coil1
 the primary circuit must be alternately
 made and broken between  one stroke and
 the next4 ,consequently proper piling  
up1 or surging1  of the current will be 
effected4 ,this is accomplished by means
 of an  interrupter that either vibrates
 rapidly or snaps once at the  formation
 of each spark4 ,the former is the more 
common type used with  battery ignition 
and is known as a vibrating coil4 ,a    
circuit breaker is  generally           
incorporated in the mechanism of a      
magneto1 and consequently  when such an 
instrument is used1 the vibrator on the 
coil is dispensed  with4 ,it is the     
vibrator on each coil that forms the    
buzz that can  be heard whenever the box
 cover is removed1 and that often       
furnishes a  simple test for determining
 the condition of the ignition system of

 the  particular cylinder with which    
that coil is connected4    ,the vibrator
 is a flat1 spring steel piece that     
rests near one end of  the soft iron    
core around which the primary coil is   
wound4 ,the springy  nature of the      
vibrator ordinarily holds it against a  
small1 adjustable  contact point that   
should be set about an eighth of an inch
 from the  end of the above-mentioned   
soft iron core4 ,the primary coil is so 
wired  that its current passes through  
the vibrator steel and the contact      
point against which it rests4 ,as soon  
as the current travels through  the coil
 surrounding the soft iron core1        
however1 the latter becomes  magnetized 
and draws the steel vibrator toward it4 
,this breaks the  circuit1 the magnetism
 of the iron core disappears1 and the   
vibrator  returns to its original       
position against its contact point4 ,but
 this  action again forms the circuit1  
and the same operation is repeated as   
long as the current is allowed to flow  

toward the coil4    ,this is the same   
principle on which an electric bell is  
rung1 but the  vibrator of the coil     
makes and breaks the circuit much more  
rapidly  on account of the less weight  
of the moving parts4 ,this vibration of 
the coil interrupter is so              
rapid--hundreds a second probably--that 
the  resulting spark is practically     
continuous and shows no effect of the   
breaks in the circuit4    ,even though  
it is the primary current1 of low       
voltage1 that is  interrupted by the    
vibrator1 the frequency of these        
interruptions  causes a slight sparking1
 or arcing1 at the contact points4      
,these are  therefore subjected to      
rather a high degree of heat1 as well as
 a large  amount of wear1 and it is     
necessary that they be made of a        
material  that will resist both4        
,platinum has been found to be unusually
 suitable  for this purpose1 but owing  
to its high cost1 only a small amount in
  the form of two points1 or buttons1 is

 used4 ,one of these points is  placed  
in the vibrator steel1 and the other is 
embedded in the end of  the screw       
against which the first rests4 ,thus the
 actual contact is  made against these  
heat-and-wear-resisting platinum points1
 and it is  evident that upon their     
proper action depends the formation of  
the  spark in the cylinder with which   
that particular vibrator is connected4  
,notwithstanding the fact that platinum 
possesses high heat-resisting           
properties1 the constant arcing at the  
contact points will eventually  form a  
sort of corrosion in which minute       
particles of the material  are carried  
from one point to the other in the      
direction in which the  current flows4  
,if the current is reversed1 the        
corrosion will take  place in the other 
direction1 and consequently the platinum
 point  that formerly lost a part of its
 material will gradually be built up    
again4 ,this corrosive action is known  
as pitting1 and while it may be  reduced

 to a certain extent by reversing the   
terminals of the battery1  as described1
 the platinum will occasionally require 
additional  attention4    ,a coil having
 badly pitted contact points on the     
vibrator will stick  and will cease to  
form a spark regularly4 ,it is often    
difficult to  distinguish between       
trouble arising from badly-pitted       
contact points  and that caused by weak 
or nearly-exhausted batteries1 as either
  ailment produces the same symptoms of 
irregular running and jerking  in the   
motor4 ,for this reason1 a volt and     
ampere meter for measuring  the pressure
 and amount of the current delivered by 
the batteries  should form a part of    
every automobile owner's tool equipment4
    ,it is the amperage1 rather than the
 voltage1 that is reduced through       
continued use of the batteries1 and when
 this quantity falls below  nine or ten1
 the cells should be discarded--or      
recharged1 in the case  of a storage    
battery4 ,but if the ignition occurs    

irregularly when the  batteries are     
delivering the proper amount of current1
 it is probable  that the trouble lies  
in the pitted condition of the platinum 
contact  points of the vibrator of the  
coil4 ,fine emery cloth rubbed over the 
surfaces of contact should serve to     
remedy matters4 ,it should be made      
certain that the resulting surfaces on  
the platinum points are not only  rubbed
 smooth1 but level1 as well1 in order   
that the entire area of  each will rest 
in contact and the current will not be  
concentrated at a  small portion4    ,it
 is probable that there will be a screw 
adjustment on the vibrator  by means of 
which the force with which the latter   
rests against its  contact point may be 
regulated4 ,if the vibrator is set too  
tight1 an  undue amount of current will 
be required to magnetize the core of the
  coil sufficiently to pull the vibrator
 away from its contact point1 and  the  
batteries will soon run out4 ,on the    
other hand1 the tension of  the vibrator

 should be sufficient to enable it to   
spring away from the  core of the coil  
as soon as the circuit is broken1 for   
otherwise the  vibrator will lag and    
will not be as lively as is necessary to
 obtain  the best results4    ,the      
contact screw should be set so that the 
vibrator rests about                    
three-thirty-seconds of an inch from the
 end of the magnetic core4  ,after the  
tension of the vibrator has been set to 
approximately the  proper amount1 the   
ear must be trusted for the correct     
adjustment of  the contact screw4 ,when 
the switch is thrown on and the motor   
turned  until current flows through the 
coil1 the resulting buzz emanating  from
 the vibrator should be decided and     
forceful4 ,if this buzz is  exceedingly 
high-pitched1 it is an indication that  
the vibrator has  been set too tight1   
and its tension should be loosened if   
unscrewing  the contact point slightly  
does not lower the tone4 ,it must be    
remembered that the tension of the      

vibrator can be changed by turning  the 
contact screw4 ,if this screw is turned 
down so that it forces the  vibrator    
toward the iron core1 the tension will  
be greater than will be  the case if the
 contact point is turned to the left4   
,if the buzz of the vibrator is pitched 
lower than was formerly the  case1 it is
 an indication that the contact point   
should be screwed  down1 or that the    
tension of the vibrator should be       
tightened4 ,it is  probable that turning
 the contact screw to the right will    
produce the  proper result4 ,while these
 changes in the position of the contact 
screw are being made1 the switch should 
be left turned on so that the           
variations in the pitch of the vibrator 
buzz may be detected4 ,when an          
evenly-pitched1 vigorous buzz has been  
secured1 the switch should be  thrown on
 and off several times to make certain  
that the response of  the vibrator is   
instant and positive4 ,the switch should
 then be left on  and the vibrator      

allowed to buzz for several seconds in  
order that it  may be determined whether
 the pitch of the sound will change1 or 
not4  ,if there is a change noticeable1 
the contact screw should be readjusted  
until the pitch of the buzz remains     
constant as long as the circuit is      
closed4    ,the coil and batteries or   
magneto by no means form the entire     
ignition  system1 although the          
generation of the spark depends entirely
 upon  them4 ,the spark must be         
regulated to occur at the proper point  
in the  stroke of the piston1 as a      
continuous spark would not only waste   
the  current1 but would cause the       
ignition of the charge during the upward
  stroke and would result in an impulse 
in the reverse direction that  would    
prevent the motor from running for more 
than half a turn4    ,the device by     
which the time of the occurrence of the 
spark is  regulated is called the timer4
 ,this consists1 in its essentials1 of a
  hard rubber disc provided with a      

copper or brass segment4 ,a metal pin1  
roller1 or ball rests against the outer 
edge of the disc1 and as the  latter is 
revolved1 the electrical circuit is     
completed whenever the  two metal       
portions come in contact with each      
other4 ,the hard rubber  being a        
non-conductor of electricity1 prevents  
the flow of the current  at all other   
times4 ,the disc of the timer1 known as 
the commutator1  is so geared that it   
revolves in unison with the motor4      
,inasmuch as the explosion occurs in    
each cylinder only at every second      
stroke of a four-cycle motor1 the       
commutator on this type of engine  is   
geared to revolve at one-half the speed 
of the crank shaft4 ,in  the two-cycle  
motor1 on the other hand1 the explosion 
occurs in each  cylinder at every       
revolution1 and consequently the        
commutator should  turn at crank shaft  
speed4    ,although the spark is        
intended to occur approximately at the  
extreme  upper end of the compression   

stroke1 a few degrees variation both    
above  and below this point is necessary
 in order to obtain the desired speed   
and power flexibility of the gasoline   
motor4 ,at high speeds1 the spark       
should be timed to occur before the     
piston reaches the extreme top  of its  
stroke1 while at slower revolutions of  
the motor the ignition  should take     
place1 in some instances1 just after the
 piston has  started to descend4 ,this  
variation ,in timing is obtained by     
swinging  the contact piece of the      
timer--known as the brush--either       
forward  or backward through an arc     
corresponding to the range of advance   
and  retard4    ,if this brush is swung 
in a direction opposite to that of the  
revolution of the commutator1 the metal 
portions will meet sooner1 with  the    
result that the spark will occur        
earlier1 or will be advanced4  ,if1     
however1 the brush is swung to a point  
farther along in the  direction of      
rotation of the commutator1 the spark   

will occur later1  or will be retarded4 
,these variations of position of the    
brush are  generally obtained by means  
of a lever attached to the steering post
 or  wheel4    ,it is evident that the  
current must pass from the brush to the 
metal  segment of the commutator in     
order to complete the circuit through   
the timer and thus form the spark4 ,it  
is the primary current1 or  low-tension 
current from the battery or magneto1    
that passes through  the timer1 and as  
this is of low voltage and is therefore 
easily  discouraged1 it is necessary    
that the contact points be kept clean in
  order that its travel may be made     
easy4 ,timers are generally protected   
from dirt1 but the particles that will  
naturally be worn off from the  metal   
and rubber commutator and brush should  
be cleaned out before its  accumulation 
becomes deposited on the contact points 
and interferes  with perfect electrical 
connection4    ,a few years ago1 the    
majority of battery ignition systems    

employed a  separate coil for each      
cylinder of the motor4 ,each coil in    
this system  is connected with an       
individual brush that operates against  
the same  commutator as do the brushes  
for the other cylinders4 ,with such a   
system1 the primary circuit leads from  
one terminal of the battery to  the     
primary winding of the coil1 through    
this and the vibrator to the  brush of  
the timer reserved for that particular  
coil and cylinder1 and  thence through  
the switch to the other terminal of the 
battery4 ,this  order may be reversed1  
or the timer1 switch1 and coil may be   
placed  in any consecutive position1    
provided the current passes through all 
in its travel from one terminal of the  
battery to the other4 ,the  secondary1  
or high-tension current is led from the 
terminal of the  secondary winding on   
the coil to the spark plug of the proper
 cylinder4  ,there should be a ground   
wire to serve for the return of the     
secondary current4 ,this may lead from  

any part of the primary circuit  to a   
clean metal connection on the motor4    
,the multiple coil system is still used 
to a large extent1 but an  elaboration  
of it will be found on many of the      
modern cars4 ,this  consists of the use 
of but a single coil for all of the     
cylinders of  the motor4 ,this is done  
by means of a distributor1 which is a   
sort of  glorified timer consisting of a
 commutator provided with as many       
segments as there are cylinders in the  
motor4 ,this distributor receives  the  
current from a single coil and delivers 
it to the proper cylinder  as the       
various connections are made4 ,the timer
 still performs its  function of        
completing the circuit from the source  
of current only at  the proper instant1 
and leaves the distributor to serve the 
purpose of  a switch to sidetrack the   
current and deliver it at the various   
cylinders in turn4    ,if it should ever
 become necessary to remove any part of 
the timer1  or to change the length of  

the spark control rods1 the greatest    
care  should be taken to make certain   
that the motor is properly timed when   
the various portions are replaced4 ,this
 can best be done by setting the  spark 
lever in its central position1 removing 
a plug from one of the  cylinders1 and  
introducing a rod or long screw driver  
into the opening  for the purpose of    
determining the exact top of the stroke 
of the  piston4 ,when the flywheel is   
turned1 the top of the stroke should be 
marked on the rod or screw driver as the
 latter is forced upward by the  piston4
    ,if the spark plug is laid with its 
large nut resting on the cylinder  head1
 and the switch is thrown1 the time of  
the occurrence of the spark  can be     
readily observed as the motor is turned 
slowly by hand4 ,this  spark should     
occur in this particular plug just as   
the piston of that  cylinder reaches the
 top of its stroke1 as indicated by the 
change in  the direction of the movement
 of the rod or screw driver4 ,if the    

spark  occurs too soon or too late1 the 
commutator should be moved backward or  
forward to remedy the respective        
trouble4 ,although if the timer is set  
properly for one cylinder it is probable
 that the spark in the others  is also  
timed correctly1 it is well to test each
 to make certain that  there has been no
 uneven wear in the contact segments of 
the commutator  or the brush4           
,,chapter ,v    ,,magnetos      ,the    
perfection of the magneto and its       
application to cars of all  classes and 
sizes has marked the most important step
 in gasoline motor  ignition since the  
introduction of the electric spark4 ,the
 magneto is  now considered one of the  
most vital parts of the car1 and while  
it is  possible for the motor to be run 
for many miles on the batteries that    
form the auxiliary ignition sources1 the
 mechanical current generator  has left 
the field of the desirable accessories  
and has become an  actual1 physical     
portion of the engine4    ,the operation

 of the magneto is simple1 its whys and 
wherefores are  logical1 and if one     
investigates the subject1 even          
superficially1 he  will discover that   
the much-maligned machine seldom gives  
trouble1  and that when it does1 such   
action1 or failure to act1 is due to    
neglect1 abuse1 or some other perfectly 
legitimate reason1 rather than  pure    
cussedness on the part of the instrument
 itself4 ,if the mere  mechanical aspect
 is considered2 if it is realized that  
the magneto  consists mainly of a bundle
 of wires which1 when revolved near the 
ends  of a magnet1 collects that        
magnetism and sends it through the      
circuit  in the form of the electric    
current1 and that consequently the      
magneto  is a converter that changes    
part of the mechanical energy of the    
motor  into the spark-forming fluid1 the
 chief idea of magneto principles may   
be more easily grasped4    ,to be sure1 
the magneto is delicate1 and for that   
reason it should  never be dissected by 

the amateur1 but inasmuch as what few   
adjustments  it has are readily         
accessible1 it is seldom that the       
machine need to  be taken apart4 ,the   
platinum points of the contact breaker1 
usually  located in the small box on the
 end of the armature shaft1 may need to 
be smoothed with emery paper            
occasionally if they have become pitted 
from excessive sparking1 but this is a  
simple operation and is not  greatly    
different from the care given to the    
vibrator of the dashboard  spark coil1  
as described in the preceding chapter4  
,a few drops of oil should be fed to the
 lubricating cups or holes of  the      
armature shaft as often as the          
directions call for--usually about  once
 every five hundred miles--but aside    
from this1 the owner can  generally     
forget that he has a magneto1 and will  
only be reminded of  the fact by the    
pleasing absence of ignition trouble4   
,if ignition  trouble does occur1 it is 
more than probable that the fault lies  

with  the plugs1 timer1 or wires1 rather
 than with the magneto4    ,the man who 
drives a magneto-equipped car knows that
 the current  producer is run by a gear 
connected1 either directly or through   
the  medium of other gears with the     
crank shaft of the motor4 ,he knows1    
then1 that the magneto is driven        
positively and that there is a  constant
 relation between its speed and the     
number of revolutions of  the motor4    
,but does he know that it is absolutely 
necessary that a certain  position of   
the armature shall always correspond    
with a similar  position of the crank   
shaft of the motor1 and that            
consequently  the same teeth of the     
driving gears must always mesh8 ,he will
 most  assuredly be made aware of this  
if he disconnects his magneto and  then 
fails to replace the gears so that      
exactly the same teeth are in  mesh1 for
 even the difference of a single tooth  
between the normal  positions of the    
armature and crank shaft will prevent   

the magneto from  delivering a          
sufficient spark to enable the motor to 
run4    ,the reason for this is simple4 
,all of these direct-driven magnetos    
are of the alternating current type1 as 
this form allows of the  simplest       
construction of armature and windings4  
,the alternating  current generator     
obtains its name from the fact that     
there are no  regularly-defined north   
and south poles at any part of the      
circuit1 as  these keep changing        
continuously1 or alternating4    ,during
 each revolution of the armature of the 
alternating current  magneto1 there are 
but two positions at which a current    
will be formed4  ,now the spark in any  
cylinder of a motor is required at about
 the top  of the compression stroke of  
the piston in that cylinder4            
,consequently  when the piston is at the
 top of its compression stroke1 ready   
for  the spark that will ignite the     
charge1 the armature of the magneto     
must be in one of its two               

current-generating positions1 and there 
must  therefore be a constant relation  
between the position of the crank       
shaft1 to which each piston is          
connected1 and that of the revolving    
part of the magneto4    ,if1 now1 the   
driving gear of the magneto is returned 
to its place  without regard to the     
teeth of the next gear with which it    
meshes1 it  will be seen that the proper
 relation between the position of the   
armature and that of the crank shaft    
will not be maintained4 ,under  these   
conditions1 when the piston is at the   
top of the compression  stroke1 ready   
for the spark1 the armature will not be 
in a position  at which a current can be
 generated1 and there can consequently  
be  no spark formed at the plug4        
,conversely1 when the armature has been 
revolved to the position at which a     
current will be formed1 none of the     
pistons will be requiring the spark1 and
 this consequent lack of team  work will
 prevent the operation of the motor4    

,in order to maintain this team work    
between the armature of the magneto  and
 the crank shaft of the motor1 the      
intermeshing teeth of the gears  should 
be marked with a prick punch before they
 are removed1 so that  they may be      
returned to their proper place without  
trouble4 ,only in  this manner can      
accurate results be obtained1 if it is  
at any time  necessary to remove all or 
part of the magneto driving gear4       
,the magnets forming the fields of the  
magneto in which the armature  revolves 
are of the permanent kind2 that is1 they
 do not depend upon  windings and a     
separate electric current for their     
excitation1 as  is the case with some of
 the larger generators4 ,these magnets  
may  be considered to be the most       
faithful part of the machine1 for they  
generally retain their strength under   
all conditions of rest or work1  and it 
is upon them that the proper operation  
of the magneto largely  depends4    ,a  
magneto in which the magnets have become

 weakened is useless for  ignition      
purposes until the fields can be        
remagnetized1 and as this  can only be  
done at the factory1 the machine in its 
entirety must be  removed from the      
motor4 ,it is a comparatively easy      
matter to determine  whether or not the 
fields have lost their magnetism by     
placing a  piece of iron or steel within
 close range of the base or sides of the
  magneto4 ,an appreciable pull will be 
exerted by the magnets if they  still   
retain their strength1 although it is   
not to be supposed that the  force thus 
exhibited will be very vigorous from    
such a small machine4    ,if the magneto
 has been disconnected from its driving 
gear for any  reason1 the amount of     
magnetism remaining in the fields will  
be best  determined by turning the      
armature shaft with the hand4 ,a        
resistance  should be offered to the    
turning at first until a certain point  
is  reached1 after which the armature   
should exhibit a strong tendency to  fly

 forward to a new position1 one hundred 
and eighty degrees beyond  its former   
normal position of rest4 ,this activity 
of the armature is  one of the best     
guides to the amount of magnetism       
remaining in the  fields4    ,many      
magnetos that have been installed on old
 motor cars not  previously so equipped 
are of the friction-driven1             
direct-current type  that produces a    
uniform spark at any point throughout   
the armature  revolution4 ,current from 
these may be used to charge a storage   
battery  for the operation of electric  
lights or to supply auxiliary ignition  
current for starting4 ,the              
positively-driven1 alternating-current  
magneto may also be used to operate     
electric lights on the car1 but  this   
type of current cannot be stored in a   
battery1 and consequently  the lights   
are available only when the motor is    
running4 ,the magneto1  however1 is not 
primarily an electric-lighting outfit1  
and unless it is  especially designed   

for the double purpose1 a separate      
machine should  generally be used for   
supplying illuminating current4         
,,chapter ,,vi    ,,carburetors ,,and   
,,their ,,fuel      ,although gasoline  
is inflammable in its liquid state1 its 
combustion  is not sufficiently rapid to
 approach the explosive point necessary 
to render its energy available in the   
automobile engine cylinder4 ,the  proper
 proportion of gasoline vapor and air1  
however1 forms a mixture  that is highly
 inflammable and that will be entirely  
consumed in the  engine cylinder under  
ordinary conditions within about        
one-twentieth  of a second after the    
formation of the spark4 ,this rapid     
combustion  so nearly approaches the    
instantaneous action of an explosion    
that it  may be considered as such in   
all ordinary discussions of the gasoline
  engine4 ,literally1 however1 the      
gasoline engine is not an explosion     
motor1 but rather is it an engine of the
 internal combustion type4 ,to  obtain  

this gasoline vapor in an               
easily-controlled form the carburetor   
was designed as one of the most         
important adjuncts of the automobile4   
,the first form of carburetors1 or      
vaporizers1 as they were called  then1  
employed a flat1 woven lamp wick over   
which the gasoline flowed4  ,this spread
 the fuel out over a comparatively large
 surface and  rendered evaporation rapid
 and simple4 ,the chamber containing    
this  wick was placed in the line of the
 intake pipe of the motor and was       
connected with the cylinders on the     
descent of the pistons on the  suction  
stroke through the medium of the various
 inlet valves4 ,in  a four-cycle motor1 
the piston acts as a suction pump on    
alternate  down-strokes and serves to   
draw the charge into the cylinder4 ,this
  suction created the necessary current 
of air to facilitate evaporation  of the
 gasoline on the wick1 and by regulating
 the size of the  passages1 the proper  
proportion of air and gasoline vapor    

could be  obtained4    ,the modern1     
high-speed automobile motor1 with its   
varying demands upon  the carburetor1   
created the necessity for a more        
delicate1 flexible1  and compact        
vaporizer than was to be found in the   
lamp wick type4  ,consequently the wick 
was replaced by a small1 slender1 hollow
 tube  having a cone-shaped opening at  
its upper end through which the         
gasoline from the feed pipe was made to 
pass4 ,fitting into the upper  end of   
this tube1 and pointed to the same      
angle1 was a cone-shaped  needle that   
could be moved in and out of the        
opening4 ,if this needle  was unscrewed 
slightly so that it did not form a tight
 fit with the end  of the tube1 a small 
ring would be formed through which the  
gasoline  must pass when sucked by the  
alternate down strokes of the pistons4  
,this tube and needle constitute1 under 
various guises1 the needle  valve with  
which practically every modern          
carburetor is equipped4    ,when the    

gasoline1 rushing through the small     
tube1 strikes the  restricted opening of
 the needle valve1 it is broken up into 
a fine  spray which1 under proper       
conditions1 will become vaporized almost
 as  soon as it comes in contact with a 
current of air4 ,this air current is    
induced by the same pump-like effect of 
the pistons as that which sucks  the    
gasoline through the needle valve1 and  
thus it occurs only when the  charge is 
desired in the cylinders4    ,but the   
carburetor is not merely to provide a   
compact device for  vaporizing the      
gasoline1 for it must also furnish a    
means of regulating  the proportion of  
gas to air4 ,gasoline vapor is only     
highly inflammable  when mixed with the 
proper quantity of air1 and if this     
proportion is  varied above one limit or
 below another1 ignition of the charge  
will  not occur in the cylinders4 ,in   
fact1 the allowable variation in the    
proportion of gasoline vapor to air is  
restricted between very narrow  limits1 

and should not change more than four or 
five per cent4 from  one extreme to the 
other4 ,the proportion of gasoline vapor
 to air by  weight is about one to      
eleven1 although this will vary somewhat
 with  the different grades of fuels4   
,the point to be emphasized1 however1 is
 the fact that the proper  proportion of
 air to gasoline vapor1 however it may  
vary with different  grades1 should be  
kept constant at all speeds of the motor
 whenever  that particular grade of fuel
 is used4 ,by volume1 about #ig per     
cent4 of the mixture should be air and  
the remainder gasoline vapor1  and it is
 the device that will the most nearly   
maintain this proportion  under all     
conditions of speed1 temperature1 and   
air pressure that will  prove to be the 
most delicate and flexible carburetor4  
,a carburetor may be adjusted for       
different motors1 or for different      
operating conditions of the same motor1 
by means of the needle valve4  ,the     
farther end of the slim rod on which the

 needle point is mounted  terminates in 
a thread and finger nut that projects   
through the shell  of the carburetor4   
,by turning this nut in one direction1  
the needle  valve is screwed up toward  
the cone-shaped end of the tube and the 
orifice through which the gasoline may  
pass is thus reduced in size4  ,this    
will decrease the amount of gasoline    
sprayed into the air passage  and will  
consequently change the composition of  
the mixture4 ,this1  however1 should not
 be confused with throttling the motor4 
,when the  needle valve is tightened1   
the volume of the mixture passing to the
  cylinders is the same1 for it is only 
the proportion of gasoline vapor  in    
that mixture that is changed4           
,throttling consists in restricting the 
size of the opening through  which the  
mixture passes1 and thus limits the     
amount of the  charge that reaches the  
cylinders at each suction stroke of the 
piston4 ,throttling is used to reduce   
the power--and consequently the         

speed--developed by the motor1 while a  
decrease in the amount of  gasoline     
supplied to the air through the needle  
valve may serve to  increase the power  
through an improvement in the nature of 
the mixture4    ,since the gasoline     
vapor1 by volume1 forms only about three
 per cent4  of the explosive mixture    
admitted to the cylinders1 a slight     
variation  in the size of the needle    
valve opening will result in a marked   
change  in the composition of the charge
 and may make all the difference        
between poor and perfect running of the 
motor4 ,consequently the needle  valve  
nut should be moved but the small       
fraction of a turn for each  adjustment4
 ,a motor which may refuse absolutely to
 run at one position  of the needle     
valve may give perfect results if the   
nut is unscrewed  but the eighth of a   
turn4    ,in view of the marked         
difference in the results obtained from 
the use  of mixtures that are just      
right1 and those which vary but a slight

  percentage in the proportion of       
gasoline vapor to air1 it may be well   
to examine1 superficially1 the effects  
of rich and weak charges1  and therefrom
 to obtain a list of symptoms which may 
aid us to  diagnose motor trouble       
properly4    ,we all know that air--or  
oxygen--is required to support          
combustion4  ,snuffing a candle is      
merely covering its end so that air     
cannot reach  the flame4 ,for the same  
reason1 gasoline in a covered tank      
cannot burn1  no matter how great the   
heat applied to it4 ,the heat of the    
electric  spark in the cylinder1        
although intense1 does not cover a      
sufficiently  large area to ignite any  
charge except that composed of the      
proper  proportion of gasoline vapor and
 air4 ,if there is too much gasoline    
vapor1 making a rich mixture1 there will
 not be sufficient air in  the charge to
 support the entire combustion of the   
gas1 and the burning  will be slow--if  
it takes place at all4 ,the same        

conditions will  prevail if there is an 
insufficient supply of air for a given  
quantity  of gasoline vapor1 and        
consequently a rich mixture may be      
obtained  by reducing the air flow as   
well as by adding to the amount of gas  
admitted to the mixing chamber4    ,a   
rich mixture will cause irregular       
explosions in the cylinders1 and  will  
often emit a black1 pungent smoke at the
 exhaust4 ,the motor will  probably     
overheat easily1 due to the slow-burning
 properties of the  mixture and the     
resulting fact that a large portion of  
the cylinder  walls uncovered by the    
pistons will be exposed to the flame4   
,in some  instances1 the cylinders will 
miss fire at regular intervals1 thus    
changing the synchronism of the impulses
 with a well-defined and  periodic skip 
in the sound of the explosions4         
,while these are by no means certain    
symptoms of a rich mixture1  the first  
test to be made should be to tighten the
 needle valve  adjustment slightly when 

the motor is running and to note any    
resulting  improvement in the regularity
 of the explosions4 ,it may sometimes be
  difficult to distinguish between the  
symptoms of a rich and a weak  mixture1 
but the readjustment of the needle valve
 as just described  will at least serve 
to locate the trouble or to eliminate   
one or the  other possibility from      
consideration4    ,when a mixture is    
starved1 or when there is an            
insufficient supply  of gasoline vapor  
to unite with the air admitted to the   
cylinders1 the  charge will not be      
highly inflammable and may not be       
ignited by the  small spark formed at   
the plug4 ,even when ignition does take 
place1 the  resulting power impulse will
 be weak because of the comparatively   
small  amount of pressure-producing gas 
in the mixture4 ,the explosions may     
occur regularly for a while1 but there  
will be a marked decrease in the  power 
developed by the motor1 and owing to the
 fact that weak mixtures  may be        

slow-burning1 back-firing will often    
result in some engines to  which such a 
charge has been fed4    ,on the other   
hand1 if a motor will run at all on a   
weak mixture1 it  will produce better   
results than would be the case were the 
charge  too rich in gasoline vapor4     
,consequently the needle valve should be
  closed as much as is consistent with  
smooth running of the motor1 but  the   
moment a loss of power or irregular     
explosions occur1 the mixture  should be
 enriched4    ,at low speeds of the     
motor1 the pumping action of the pistons
 is not as  great as is the case at high
 revolutions1 and consequently the      
suction  drawing the gasoline through   
the needle valve is diminished4 ,for    
this  reason1 the needle valve opening  
must be made larger or the air passage  
restricted for slow speeds of the motor1
 and it was consequently  necessary1 on 
the old1 non-automatic vaporizers1 to   
increase the  gasoline supply whenever  
the revolutions of the motor were to be 

reduced4 ,the modern carburetor is      
sufficiently automatic in its action  to
 provide the proper mixture within wide 
ranges of speed change of the  motor1   
but even nowadays it is often found     
necessary to increase the  gasoline     
supply or to reduce the amount of air   
admitted to the intake  pipe whenever it
 is desired to throttle the motor down  
to a very low  number of revolutions per
 minute4    ,the automatic action of the
 ordinary carburetor is obtained by     
increasing the air supply at higher     
speeds of the motor4 ,consequently  the 
motorist will realize that whenever the 
needle valve is to be set1  such        
regulation should be made when the motor
 is well throttled1 for  if an ample    
gasoline supply is obtained at low      
speeds1 the mixture  will certainly be  
sufficiently rich at increased          
revolutions4 ,if1 on  the other hand1   
the carburetor should be set to supply a
 proper mixture  at high speeds1 the    
mixture would be impoverished when the  

motor is  throttled1 and irregular      
running would result4    ,the air for   
the operation of the motor at ordinary  
speeds is supplied  through a fixed     
opening in the carburetor connected with
 the chamber  into which the gasoline   
spray is introduced4 ,in addition to    
this1 most  carburetors are supplied    
with an auxiliary air opening which     
serves  to furnish the additional air   
necessary for the mixture at high speeds
  of the motor4 ,the fixed opening1     
being restricted in size1 cannot  admit 
the increased quantity of air demanded  
by the higher speeds  of the motor4 ,the
 auxiliary opening is provided with some
 form of  automatic valve which may     
consist either of a series of ball      
checks1  a spring-actuated mushroom     
valve1 or a series of special valves1   
each  of which opens at successively    
increased speeds of the motor4    ,all  
of these devices operate on the same    
principle1 however1 and  allow the      
increased suction of the motor to add to

 the size of the  air passage           
automatically--either by the farther    
opening of a  single valve1 or by the   
successive opening of different valves4 
,some  carburetors are provided with an 
adjustment by means of which the        
delicacy1 or ease of opening1 of the    
auxiliary air valve may be  regulated4  
,this may be done by means of a nut and 
screw which will  increase or decrease  
the tension of the controlling spring4  
,if this  spring is set with a high     
tension1 the auxiliary valve will act   
only  when the motor is exerting great  
suction1 or at fast speeds4    ,the     
regulation of the auxiliary valve is an 
adjustment that should be  made only    
after the needle valve has been set     
properly for slow speeds  of the motor4 
,when this condition is obtained1 the   
throttle should be  opened and the      
further adjustment of the carburetor for
 high speeds of  the motor should then  
be made through the auxiliary air valve4
 ,in other  words1 the needle valve     

should be set so that the motor runs    
properly  at low speeds1 while the      
adjustment of the auxiliary air valve   
should  be made only to secure smooth   
operation at a high number of           
revolutions4    ,it is not to be        
understood that less gasoline is        
actually required at  high speeds of the
 motor because the supply often needs to
 be cut down  at the needle valve under 
these conditions4 ,the actual amount    
required  at high speeds is1 of course1 
greater than is the case at slow1 on    
account of the greater number of        
explosions in the former instance4 ,but 
the suction of the motor generally      
increases the gasoline flow beyond  the 
demands of the cylinders at high speeds1
 and it is for this reason  that the    
automatic auxiliary air supply is       
provided to furnish the  additional air 
required to support combustion4 ,in     
fact1 at heavy loads1  when the total   
amount of gasoline consumed must be     
great1 a secondary  jet of fuel is      

brought into action in some carburetors4
 ,this is known  as the multiple-jet    
type and is found on some of the large  
engines  that must possess a speed and  
power variation between wide ranges4    
,the  action of these various jets is   
entirely automatic and is dependent     
upon the speed and fuel requirements of 
the motor4    ,were the gasoline fed    
directly from the fuel tank to the      
needle valve  of the carburetor it is   
evident that the rate of flow of the    
liquid  would depend1 to a large extent1
 upon the amount in the tank and upon   
the position of the car4 ,this would    
cause each charge to differ in the      
proportion of gasoline vapor to air1 and
 it is hardly probable that the  motor  
could be run at all under such          
conditions4 ,in order that the  pistons 
may suck the gasoline from a level that 
does not vary with  the amount of fuel  
in the tank or the position of the car1 
a separate  compartment is provided in  
the carburetor4 ,this is known as the   

float  chamber1 and it is from this     
compartment that the gasoline passes    
through the needle valve into the       
vaporizing or mixing chamber4    ,a cork
 or hollow metal float is placed in this
 float chamber and is  mounted on a     
lever connected with a valve located at 
the end of the  gasoline feed pipe4 ,as 
the gasoline is admitted to the chamber1
 the  float rises and closes the valve  
controlling the flow of fuel4 ,as the   
gasoline is sucked through the needle   
valve from the float chamber1  the float
 in the latter lowers1 and the fuel is  
again admitted by  the opening of the   
above-described valve4 ,the float and   
valve are  exceedingly delicate in their
 operation and the gasoline is thus kept
  at a constant level in the chamber    
under all conditions of the car and     
tank4    ,the stem upon which the float 
of some carburetors is mounted is       
sometimes threaded and provided with a  
nut by means of which the float  may be 
raised or lowered4 ,this furnishes an   

adjustment for varying the  level in the
 float chamber and determining at what  
point the flow  of gasoline shall be cut
 off by the automatic valve4 ,the float 
is  supposedly properly regulated when  
the carburetor leaves the factory1  but 
the stem may become bent or the         
carburetor may be applied to a  motor   
other than that for which it was        
originally designed4 ,in either  of     
these events1 it may be found necessary 
to raise or lower the float  before the 
proper level of gasoline can be         
maintained in the chamber4    ,if the   
float is too high on its stem1 the      
gasoline control valve may  not be      
operated until the fuel overflows in its
 chamber4 ,this is known  as a flooded  
carburetor and produces a rich mixture  
which will  ultimately prevent the      
proper operation of the motor4 ,turning 
down  the gasoline supply at the needle 
valve will not remedy this1 for the     
fuel will reach the vaporizing chamber  
by another route4 ,a flooded  carburetor

 often gives trouble1 and while it may  
be remedied easily1  the amateur may    
experience difficulty in locating its   
source4    ,as soon as it is discovered 
that a carburetor has become flooded1   
the  needle valve should be tightened so
 that no gasoline can pass through  it1 
and the motor should then be cranked4   
,this will serve to evaporate  the      
excess gasoline in the float chamber and
 reduce the level to the  point at which
 it will not overflow4 ,the exact number
 of turns and  fractions of turns       
through which the needle valve nut was  
moved should  have been noted in order  
that the valve may be reset to its      
original  position after the surplus    
fuel has been cranked out4    ,a float  
that is set too low on its stem will    
close the fuel supply  valve before a   
sufficient amount of the fuel has flowed
 into the  chamber1 and will form a lean
 mixture at high speeds of the          
motor--even though the needle valve     
should be opened wide4 ,the obvious     

remedy for such a condition is to raise 
the float until the gasoline  will be   
maintained at the proper level4 ,if     
there is no nut and screw  adjustment by
 which the float may be raised1 the arm 
to which it is  attached1 and which is  
connected with the valve1 may be bent   
slightly4    ,but the motorist should   
not jump at conclusions and assume that 
the  float is improperly set the moment 
the carburetor begins to flood or  the  
motor appears to starve at high speed4  
,the first condition may be  caused by a
 piece of dirt or other foreign matter  
that may have become  lodged on the     
valve seat and prevented the valve from 
closing when  the gasoline reached the  
proper level in the float chamber4 ,this
 will  produce exactly the same results 
as will a high float and is a trouble   
that will more often occur in the       
average carburetor4    ,the difficulty  
may generally be remedied easily by     
draining the  gasoline from the float   
chamber after the valve in the main     

supply  pipe has been turned off4 ,the  
offending foreign matter will generally 
be carried with the gasoline as the     
latter is drained1 and the valve  in the
 feed pipe may again be opened as soon  
as the drain cock is  shut off4 ,if this
 fails to remedy matters1 it is probable
 that the  difficulty lies with the     
float4    ,a clogged gasoline pipe or   
dirty strainer will produce the same    
effect  on the operation of the motor as
 will a float that is set too low on    
its stem4 ,when the motor seems to      
starve at high speed1 and it is  evident
 that there is sufficient gasoline in   
the tank1 the union should  be          
disconnected at the point where the feed
 pipe joins the carburetor4  ,if there  
appears to be an ample flow through this
 pipe when the main  valve is opened1 it
 is probable that the stoppage has      
occurred in the  strainer4 ,if the flow 
through the main feed pipe is not free1 
however1  it is possible that the vent  
hole in the filler cap on the tank has  

become stopped or that the latter has   
been screwed down too tightly4 ,in  the 
gravity feed systems1 some method must  
be provided to allow the air  to flow   
into the tank to replace the gasoline   
fed to the carburetor4 ,if  there is no 
hole in the filler cap1 the latter      
should not be screwed  down so tightly  
that an airtight joint will be formed4  
,probably the simplest method of        
determining whether the trouble lies  in
 a low float is to prime the carburetor 
and to observe the ease with  which this
 can be done and its effect upon the    
engine4 ,nearly every  carburetor is    
provided with a flushing or priming pin 
by means of  which the float can be     
depressed so that the gasoline chamber  
will  be filled rapidly to a point above
 its normal level4 ,this is useful  in  
starting1 as the desired rich mixture is
 quickly obtained without  an undue     
amount of cranking4 ,if the carburetor  
flushes easily1 it  is evident that     
there is no serious stoppage in the     

pipe4 ,if this  easy flushing is        
followed by good running on the part of 
the motor1  and if this1 in turn1 is    
succeeded by gradually-diminishing      
impulses  indicating a weakening        
mixture1 it is quite evident that the   
float is  preventing the flow of the    
gasoline at the proper time4    ,in     
addition to the flush pin found on      
carburetors1 many are provided  with    
other devices to render starting easy4  
,it is well known that a  high-test     
gasoline1 such as a #gf1 will vaporize  
more easily than will  one of a lower   
degree of specific gravity4 ,also1 every
 motorist has  had impressed upon him   
the fact that heat aids in the          
vaporization of  gasoline4 ,if we try to
 start a motor on a cold morning with a 
low-grade  gasoline1 such as the #fj- or
 #fb-;degree fuel now generally         
obtained1 we  know that a rag dipped in 
hot water and wound around the          
carburetor  will help matters4    ,to   
enable low grades of fuel to be properly

 vaporized under all  running           
conditions1 many carburetors are        
provided with a water jacket            
surrounding the vaporizing chamber4     
,this jacket is connected with the      
cooling system of the motor1 and the hot
 water surrounding the chamber  so warms
 the interior that vaporization is      
greatly facilitated4 ,some of  these    
systems are provided with a shut-off    
cock by means of which the  carburetor  
may be operated with hot water in the   
jackets1 or not1 as  desired4    ,other 
carburetors employ a jacket surrounding 
the exhaust pipe of the  motor and      
connected with the vaporizing chamber4  
,the air is heated by  the hot exhaust  
pipe as it is sucked into the           
carburetor1 and this also  facilitates  
the vaporization of the fuel4 ,some     
carburetors are provided  with both     
jacket systems1 while others have       
neither1 but whatever  design is        
installed1 the best results will be     
obtained if cold air is  used after the 

motor is once started4 ,cold air is more
 concentrated  and contains a greater   
amount of oxygen per cubic foot than    
does air  that has been expanded by     
heat1 and consequently many carburetors 
are  provided with a means of turning   
off the hot air after the motor is      
started4    ,the higher the degree of   
specific gravity of a fuel on the ,baum 
scale1  the more volatile will it be1   
and consequently a #fh gasoline will    
vaporize more easily and give more power
 than will a #fj or #fb fuel4  #gb      
gasoline is often used in races1 but the
 average motorist does  not get better  
than #fd--;and he is sometimes lucky to 
obtain fuel of  that specific gravity4  
,a hydrometer1 or specific gravity      
tester1 is a  convenient instrument for 
the average motorist to own1 and with it
 he  may tell exactly what grade of fuel
 he is paying for4 ,the ,baum scale1  by
 which all gasoline is tested1 reads in 
degrees1 and the specific  gravity is   
obtained by observing the depth to which

 the hydrometer  sinks in the liquid4   
,this instrument resembles somewhat a   
glass  thermometer1 and is so graduated 
that the deeper it sinks in a liquid1   
the higher will be the reading on its   
scale4    ,water in the fuel is an      
annoyance that is often encountered by  
the  automobilist and the motor boatman1
 and this will make its presence  known 
by causing the motor to skip when all   
adjustments and connections  seem to be 
in perfect condition4 ,water is much    
heavier than gasoline  and has no       
affinity for it1 and consequently1 as it
 sinks to the  bottom of the tank1 a few
 drops in a large amount of gasoline    
will  cause trouble by passing out      
through the needle valve at intermittent
  intervals and forming an unexplosive  
mixture4    ,the presence of the water  
in the fuel may be detected easily      
without  the use of a hydrometer by     
drawing some gasoline from the bottom of
  the tank into a tin or white-enameled 
cup4 ,if water is present1 it may  be   

seen in the form of small globules in   
the bottom of the cup4 ,if the  contents
 of the cup are poured over a flat      
surface so that the liquid  may be      
allowed to spread1 the gasoline will be 
seen to cover a large  surface and      
evaporate quickly1 while the water will 
seem to remain  in the globules         
unevaporated for some time after the    
gasoline has  disappeared4 ,this latter 
test will sometimes show the presence of
 water  when none can be discerned in   
the bottom of the cup before the        
contents  are poured out on the flat    
surface4    ,the practice of doping the 
fuel tank by adding to the gasoline     
ether  or some other highly volatile    
liquid is not to be recommended to the  
average motorist4 ,a few ounces of ether
 or chloroform added to the fuel  will  
form a more volatile and consequently   
more powerful mixture1 but  unless the  
greatest care is taken1 the motor is    
liable to be completely  ruined by such 
a procedure4 ,numerous cases are on     

record in which  cylinder heads have    
been blown off or castings cracked by   
the force of  some of the explosions    
when too much dope has found its way    
into the  mixture4    ,although the     
average motor gasoline obtainable       
nowadays is hardly all  that could be   
desired as automobile fuel1 a little    
care taken when  filling the tank will  
eliminate many of the carburetor        
annoyances to  which many cars seem to  
be subject4 ,the cap of the tank should 
never  be taken off when the air is     
filled with particles of dust that are  
liable to find their way into the fuel1 
and care should be taken to  see that no
 pieces of the rubber or leather washer 
or packing drop into  the gasoline when 
the cap is removed4 ,foreign matter and 
water that may  be in the gasoline when 
purchased may be removed by straining   
the fuel  through a chamois skin placed 
inside of the funnel through which the  
tank is filled4          ,,chapter ,,vii
    ,,lubrication      ,a lubricant acts

 as a sort of pacifier between two      
surfaces that  would otherwise move in  
contact with each other4 ,no surface can
 move  in direct contact with another of
 the same or a different material       
without the generation of heat2 but the 
amount of heat generated1 or  resistance
 met with1 is determined by the nature  
of these two rubbing  surfaces4 ,the    
oil1 or grease1 or whatever suave1      
slippery substance is  to be used as a  
lubricant1 interposes itself in a thin  
film between  the two rubbing surfaces  
and smooths matters over1 as it were4   
,if a  sufficient amount of this        
mechanical soothing syrup is not fed to 
the  rubbing surfaces1 the temper and   
temperature of each will be raised to   
the point where they will clinch1 and   
much time and effort may be  required   
before harmony can again be restored4   
,thus it is actually upon a film of     
lubricant that a shaft rests1 rather    
than upon the bearing1 or box1 in which 
it turns4 ,if the bearing  is set so    

tight that there is no room for the     
interposition of an oil  film1 the shaft
 and journal will at once heat4 ,the    
greater the pressure  of the shaft in   
its box1 the thicker1 or heavier1 should
 be the  lubricant used1 for a light oil
 would be squeezed out or broken down   
more easily than would one that         
possesses greater viscosity4    ,the    
coefficient of friction may be termed   
the mechanical amount of  irritability  
generated when two surfaces are rubbed  
together4 ,thus if  two metals are      
rubbed together1 this figure is high1   
and a large amount  of friction1 or     
heat1 will be generated4 ,a metal       
rubbing over oil1  however--as is the   
case with a well-lubricated             
bearing--will arouse but  little        
resentment and its pathway will be made 
smooth and easy1 for the  coefficient of
 friction of these two materials is low4
 ,the lower this  figure can be kept1   
the more easily can the surfaces be     
rubbed over  each other and the higher  

will be the efficiency of the bearing4  
,apply this to every bearing or rubbing 
surface of a motor1 and we see  that    
proper lubrication affects not only the 
length of life of the  moving parts1 but
 the ease with which the engine can be  
run and the  consequent power           
development4 ,thus1 a lubricant that    
will prevent wear  between the moving   
parts may be supplied to the bearings   
and pistons of  a motor1 and under this 
condition the engine might last         
indefinitely2  but this oil might be so 
viscous or possess so high a coefficient
 of  friction that each bearing would   
turn with difficulty and much effort    
would be required to run the motor      
before it could begin to develop  power4
    ,but the introduction of oil to a   
bearing not only reduces the  friction  
between the surfaces that would         
otherwise move in contact  with each    
other1 but it serves another very       
important purpose4 ,every               
properly-lubricated portion of a motor  

either moves in a bath of oil  or is    
connected with an oil reservoir so that 
a certain amount will  be fed regularly 
to the rubbing surfaces4 ,there is      
always some heat  generated in a        
bearing1 no matter how well it may be   
lubricated1 and  the continuous flow or 
circulation of the oil serves to carry  
off this  heat that would otherwise tend
 to dry the lubricant if there were no  
fresh supply4    ,the proper lubrication
 of the motor is even more necessary    
than is the  adjustment of the          
carburetor or the condition of the      
ignition system4  ,to be sure1 if either
 the carburetor or the ignition system  
is out  of order1 the motor will not    
run1 but no actual harm to the mechanism
  will result from this fact4 ,on the   
other hand1 a motor may be run          
indefinitely with a defective           
lubricating system1 and no apparent harm
  will result--until the end of that    
indefinite time arrives and it is  found
 that the machine is a fit subject for a

 junk heap4    ,let us see how many     
parts of the motor are reached by the   
gallon or  so of oil that we pour into  
the tank4 ,a six-cylinder motor may have
  seven crank shaft bearings2 it will   
certainly possess six connecting  rods1 
each of which will be provided with a   
bearing at both its large  and small    
ends--or twelve in all2 there may be two
 cam shafts1 each  with five bearings   
and half a dozen cams2 these will       
require1 together  with the magneto and 
pump shafts1 five or six gears in the   
forward  train2 and the six pistons will
 demand their share of attention  from  
the lubricating system4 ,here is a grand
 total of over fifty  rubbing surfaces  
on a large motor1 and the oil must be   
thoroughly  and constantly distributed  
to each4 ,of course1 many smaller       
motors1  provided with but a single cam 
shaft and a three-bearing crank shaft1  
may possess but one-half of this number 
of lubricated parts1 but at the  least1 
the oil must reach with unfailing       

certainty two dozen vital  places of the
 engine4    ,at some of these portions1 
the movement is comparatively slow and  
the  pressure is not great4 ,therefore  
such surfaces as the cams or valve  stem
 rollers will demand less oil than will 
the bearings revolving at  higher speed 
and carrying heavier loads4 ,but it is  
the hardest-worked  bearings that form  
the majority of the friction surfaces of
 a motor1  as will be realized when it  
is remembered that all points on the    
circumference of a three-inch crank     
shaft bearing will travel at the        
approximate rate of #a1jjj feet per     
minute--and these are the portions  that
 also carry the heaviest load4    ,but  
while the pistons can hardly be called  
bearings in the  generally-accepted     
layman's definition of the term1 they   
require the  lion's share of the        
lubricant1 and are the first portions of
 the motor  to feel--and show--the      
effect of any failure of the oiling     
system4  ,while in terms of miles per   

hour1 the movement of the pistons may   
not  seem very rapid1 the thousand feet 
per minute at which each ordinarily     
travels is rather a high rate of speed  
when it is considered that it  is       
entirely a rubbing or a sliding motion1 
and that the direction  is reversed more
 than two thousand times during each    
sixty-second  period4 ,this means that  
each piston slides or rubs within the   
cylinder  walls for a distance of       
between two and three thousand miles    
during  an ordinary season4 ,and        
remember that this is not a rolling     
motion1  but a continuous rubbing6 ,in  
addition to this high-speed rubbing1 the
  pistons are pressed firmly against the
 side of the cylinders on each          
explosion stroke throughout a portion of
 their travel4 ,this corresponds  to a  
heavy pressure carried by the rubbing   
surfaces1 and is caused by  the side    
thrust induced by the angularity of the 
connecting rod as it  overcomes the     
resistance of the load through the crank

 shaft4    ,but this is only a small    
portion of the difficulties that must be
  overcome in cylinder lubrication4 ,not
 only must the oil pacify the  rubbing  
surfaces and keep them well separated1  
but it must remain  within a restricted 
territory of the cylinder walls4        
,whatever oil  reaches the upper portion
 of the cylinder walls will be burned   
and will  contribute to the formation of
 the carbon that is the mortal enemy  of
 efficient running4 ,large quantities of
 oil burned in the cylinder  will also  
form the dense clouds of choking blue   
smoke that the health  authorities of   
many cities have been investigating1    
which have led  to the enactment of city
 ordinances making the driving of a     
smoking  automobile a misdemeanor4      
,in view of the difficulty which has    
been experienced by many drivers  in    
sufficiently lubricating the pistons    
without causing the car to  emit clouds 
of smoke1 it may well be asked1 ,why    
cannot an unburnable  oil be used and   

thereby eliminate this trouble8 ,this is
 out of the  question1 for the mineral  
oils now used are obtained from         
petroleum  and are cousins of kerosene1 
gasoline1 benzine1 and many of the other
  highly-inflammable liquids that need  
but the touch of a match to  burn almost
 with the rapidity of an explosion4 ,but
 notwithstanding  the excitable family  
to which the mineral oils belong1 the   
modern  motor car lubricants are removed
 a sufficient distance from their  more 
inflammable relatives to enable them to 
withstand a temperature  of between #djj
 and #ejj degrees1 ,fahrenheit4 ,this is
 sufficient  heat-resisting ability to  
enable the oil to stay on the cylinder  
walls  near the bottom of the stroke1   
where it is most needed2 but even though
  its burning point could be raised to a
 degree double its present  amount1 it  
could not withstand the high temperature
 generated in the  top of the cylinder  
at the time of the explosion4 ,the      
temperature  here reaches a point well  

above the #bjjj-;degree mark1 and were  
it not  for the cooling system1 parts of
 the interior of the cylinder would     
probably be melted by the continued     
application of this excessive heat4     
,any oil1 consequently1 would find but  
small opportunity to remain  in its     
normal state after it once reached a    
point at which it would  be exposed to  
the heat of the explosions1 and we must 
look for a  preventive measure other    
than that of increasing the flash-point 
or  burning-point of the lubricant4 ,but
 this high temperature does not  exist  
throughout the stroke1 for as the piston
 descends and the gas  expands1 heat is 
given off until the oil on the lower    
portions of  the cylinder uncovered by  
the piston is sometimes able to remain  
in comparative peace4 ,and even though  
this oil remaining on the  cylinder     
walls at the bottom of the stroke should
 be burned1 it would  not be present in 
sufficient volume to create the dense   
clouds of  objectionable smoke4         

,consequently it is the endeavor of     
engineers so to  design the pistons and 
lubricating system that excess oil will 
not be  fed to the pistons and allowed  
to remain on the walls after the former 
have descended4    ,but an excess amount
 of oil fed to the cylinders will result
 in so  much less harm than will an     
insufficient supply1 that we are        
treading  on rather dangerous ground    
when we warn the amateur to cut down his
  lubricant to the point where there    
will be no smoke4 ,as there are no      
ordinances that absolutely prohibit the 
slightest appearance of smoke  at the   
exhaust1 and as a faint blue trail is an
 excellent indication  that the motor is
 receiving sufficient lubrication in the
 cylinders1  it forms a satisfactory    
test by which the novice can determine  
the  condition of the oiling system4    
,by the time that the exhaust gases have
 passed through the pipes  and have     
expanded in the muffler1 some of the    
blue smoke may have  disappeared1 and   

consequently the fact that a car does   
not give a  trace of vapor at its       
exhaust should not necessarily be taken 
as an  indication that the motor is not 
well lubricated4 ,if the owner would    
satisfy himself that the cylinders are  
receiving a sufficient amount of  oil1  
he may open the individual pet cock on  
each1 and if he finds there  a faint    
blue trail of smoke at each explosion in
 that cylinder1 he may  rest assured    
that harmony exists between the rubbing 
surfaces of the  piston and the cylinder
 walls4    ,with the increase in the    
size and power of the automobile motors 
and  the proportionately greater number 
of parts demanding lubrication1  the    
attention required from the driver by   
the oiling system has been  greatly     
lessened4 ,instead of the necessity of  
turning on individual oil  cups whenever
 the motor is started1 the modern driver
 merely twirls  the starting crank or   
presses the button of the self-starter1 
secure  in the knowledge that whenever  

the motor runs1 the lubricating system  
operates--provided1 of course1 the      
reservoir is filled and there is  no    
stoppage in the pipes4 ,the oiling      
system of the modern motor is           
absolutely automatic1 and if supplied   
with a sufficient quantity of a  good   
lubricant1 it will perform its work with
 an absence of trouble  that places it  
among the greatest improvements of the  
engine of recent  years4    ,individual 
oil cups such as were used formerly1    
have been eliminated  from the          
cylinders1 and whatever sight-feeds     
there may be are placed  on the dash in 
plain view of the driver4 ,instead of   
relying upon  the suction of the        
cylinders for the positive feed to the  
piston1  mechanically-operated pumps are
 used to force the oil to the various   
portions of the motor4 ,in some systems1
 there is a separate pump for  each oil 
lead4 ,this is known as a mechanical    
oiler1 and generally  consists of an oil
 tank located on the dashboard of the   

car--either in  front of the driver1 or 
under the motor hood--and connected by  
means of  a belt or gear with some shaft
 of the motor4 ,the belt or gear drives 
a shaft to which is connected the       
plungers of the various oil pumps  that 
force the oil to the different parts of 
the motor4 ,before passing  to the      
individual pipe1 however1 the oil drops 
through a sight-feed  connected with    
that lead1 and as all of these          
sight-feeds are mounted  in a row within
 plain view of the driver1 the condition
 of the  lubricating system in part or  
in whole may be determined at a glance4 
,the parts of the motor that are        
lubricated by an independent feed line  
in this manner may vary with different  
motors4 ,in general1 however1  it may be
 said that it is seldom that the oil is 
fed directly to the  piston1 but that   
the lubricant is first distributed to   
the oil wells in  the crank case4 ,here1
 the splash of the cranks as they       
revolve in the  oil is depended upon to 

throw the lubricant upon the exposed    
portion of  the piston as it            
reciprocates below the cylinder walls4  
,the sides of  the piston thus covered  
carry the oil to the cylinder walls4    
,it is evident that if an excess amount 
of oil is continually carried  up by the
 piston to the cylinder walls1 a certain
 proportion of this  lubricant will     
reach the open space in which the charge
 is ignited1  and will there be         
burned--with the attendant formation of 
clouds of  objectionable smoke4 ,this   
trouble is overcome to a certain extent 
in some motors by the use of a type of  
ring set in the piston that  prevents   
the lubricant from passing to the upper 
portion of the  cylinder2 but all the   
oil cannot thus be retained1 and it     
therefore  behooves the driver not to   
allow too great a quantity to be fed to 
the  crank case if the splash system is 
used4    ,the main bearings on which the
 crank shaft revolves are generally     
supplied with oil by independent leads  

from the oiler1 and when the            
above-described system is used they may 
be regulated independently of  the      
splash feed lubricating pipes4 ,excess  
oil at the bearings will  cause no      
damage1 but each crank shaft journal    
does not demand as great  an amount as  
that supplied to a piston and connecting
 rod bearing4    ,many lubricating      
systems that are now in popular use     
employ but one  pump to force the oil to
 the various bearings and rubbing       
surfaces1  and regulate the supply by   
the size of the pipe leading to each4 ,a
  satisfactory method of overcoming the 
possibility of excess oil in  the       
cylinder has been adopted by some       
manufacturers4 ,this consists in        
placing a channel1 or trough1 directly  
under the lower sweep of each           
connecting rod bearing4 ,each channel is
 kept filled to overflowing  by a       
separate pipe connected with the main   
lead from the pump1 and a  constant     
level is consequently maintained at all 

speeds of the motor4  ,an elaboration of
 this method consists in attaching one  
end of each  trough to a rod operated in
 conjunction with the throttle1 so that 
as the speed of the motor increases1 the
 end of the channels may be  tilted1    
with the result that the connecting rod 
scoop will dip deeper  into the         
lubricant4    ,after the proper level in
 each trough has been reached the excess
 oil  overflows into the bottom of the  
crank case4 ,from here1 it is again     
started on its way by the pump and is   
distributed to the various  bearings and
 troughs through the different pipes    
leading from the pump4  ,as a further   
precaution against a smoking exhaust1   
some designers have  added a baffle     
plate above each crank case compartment 
that serves to  reduce the size of the  
opening through which the oil may be    
splashed4  ,with this combination of    
troughs and baffle plates the           
possibility of  a smoking motor is      
practically eliminated4    ,all motors  

are not so equipped1 however1 and in the
 case of those  provided with the       
bona-fide splash system1 care must be   
taken to keep  the separate crank case  
compartments filled to the proper level4
 ,too  high a level in the crank cases  
will cause the motor to smoke2 while    
the supply should not be allowed to     
become so low that when the angle  of   
the crank case is changed--as in        
ascending a hill--the lubricant  will   
run toward the rear and will not be     
reached by the scoop on the  connecting 
rod bearing4 ,this latter danger makes  
it advisable to give  this system plenty
 of oil when any touring is to be done  
through a  hilly district4    ,in some  
lubricating systems1 the oil is supplied
 as it is used1 and  either is          
discharged with the exhaust1 or collects
 in the bottom of  the crank case1 from 
which it should be drained occasionally4
 ,in the  circulating systems1 however1 
which are now used on a majority of the 
cars1 the same oil is used continuously 

until it becomes worn or  filled with   
sediment and particles of dirt and other
 foreign matter4  ,the pump used for    
maintaining this circulation may be     
either of the  plunger1 centrifugal1 or 
gear type1 and is generally housed in a 
portion of the crank case4 ,a strainer  
is usually placed in the suction  end of
 this pump for the purpose of removing  
all the free foreign  matter from the   
oil before it is again started on its   
mission of  lubrication4 ,in these      
systems1 the oil well is generally      
located in a  secondary bottom of the   
crank case4 ,from here it may be drained
 when  the supply is to be renewed4     
,another successful system by which all 
the bearings of the crank shaft  are    
positively lubricated is used on many of
 the best cars4 ,in this  system1 a     
continuous oil hole passes throughout   
the length of the  crank shaft1         
including its arms and connecting rod   
bearings4 ,at each  bearing1 one or two 
small oil holes connect with this main  

artery and  extend radially to the      
surface4 ,oil is forced into the        
longitudinal  oil hole by means of a    
small pump1 and naturally finds its way 
through  every radial opening to all the
 bearings4 ,the excess may overflow into
  the individual oil wells1 from which  
it will be splashed upon the  exposed   
portions of the pistons as they descend4
    ,it will be seen that1 no matter    
what modern oiling system is used1 the  
same kind of lubricant is supplied to   
all parts of the motor4 ,this  feature  
makes matters much simpler than was the 
case when one oil was  used for the     
cylinders1 another1 of a different      
thickness1 supplied to  the crank case1 
and still a third required for the      
gears4 ,by the old  gravity systems1 the
 flow of oil depended largely upon its  
viscosity1  or thickness4 ,therefore1 in
 winter1 a thinner oil was required than
  in summer1 for the more a lubricant is
 warmed1 the thinner does it            
become--and vice versa4 ,with the       

mechanical force systems now in use1    
however1 practically the same kind of   
oil may be used throughout the          
year--although many motorists believe   
that better results will be  obtained if
 a heavier oil is used in summer than in
 winter4 ,the oil  will be warmed by the
 motor and it will not require many     
minutes of  operation before a lubricant
 made thick by a low temperature will   
flow  freely and do its work as         
efficiently as a thinner oil4    ,but no
 matter how reliable a lubricating      
system may be in its  operation1 the    
driver must do his share and make       
certain that fresh oil  of the proper   
quality is supplied when needed1 and    
assure himself that  all the passages   
are free from obstructions4 ,negligence 
on the driver's  part may result in one 
or more stuck pistons that will either  
seriously injure the motor1 or will put 
it out of commission until the  trouble 
can be remedied4 ,if a sufficient supply
 of oil is not fed to  the rubbing      

surfaces between the piston and the     
cylinder walls1 a high  degree of heat  
is generated which will tend to expand  
the piston until  it grips the cylinder 
so closely that the former cannot be    
moved4 ,in  this event the motor will   
stop dead1 and cannot be started again  
until the piston has cooled and         
contracted to its normal size4 ,even    
then1 however1 the motor should not be  
run under its own power until  the      
burned and gummed oil has been removed  
and the scored surfaces have  been      
cleaned4 ,while this may best be done by
 removing the piston--at  which time an 
examination for any badly burned rings  
may be made--this  is not always        
possible1 and it may be necessary to run
 the car home or  to the nearest repair 
shop before the proper repairs can be   
made4    ,in this case1 the motor should
 be turned by hand until it is certain  
that the piston is again free in its    
cylinder4 ,liberal quantities of        
kerosene oil should be poured in through

 the spark plug opening1 and if         
possible1 the motor should be rocked    
back and forth by the flywheel  to give 
the kerosene an opportunity to reach all
 parts of the piston  and rings4 ,the   
kerosene will serve to cut and remove   
much of the carbon  and gummed oil and  
to make the way free for the fresh      
lubricant1  which should be poured in   
liberal quantities into the cylinder    
head4  ,the flywheel should again be    
moved back and forth so that the oil    
will  reach all parts of the piston     
surface1 and after this--if the damage  
has not been too great--the motor should
 be ready for operation4                
,,chapter ,,viii    ,,cooling      ,to  
enable the parts of a motor to work     
well1 there must be freedom of  motion  
between all that move in contact with   
each other4 ,this necessary  freedom of 
motion is provided for to a certain     
extent by proper  lubrication1 but this 
is not all-sufficient4 ,the necessity   
for some  additional friction- and      

heat-reducing system can be better      
realized  when it is understood that the
 temperature of the explosion in the    
cylinders of a gasoline engine is well  
over #b1fjj degrees1 ,fahrenheit4  ,the 
melting point of pure iron is less than 
#b1hjj degrees4 ,therefore  were there  
no escape for this heat1 and could the  
motor be induced  to run under these    
severe conditions1 the cylinders would  
soon reach  a temperature dangerously   
near the melting point4 ,long before    
this  point could be reached1 however1  
the intense heat would have expanded    
the pistons so that they would become   
stuck in their cylinders1 and  no more  
explosions could occur4 ,an ominous     
knock in one or more of  the cylinders1 
followed by a sudden laboring and final 
cessation of  operation on the part of  
the motor1 is sometimes the first       
intimation  that the driver may have    
that his engine is over-heated2 but     
serious as  a stuck piston may seem1 it 
is fortunate that the motor stops of its

  own accord1 for to continue to run    
under these conditions of constantly    
increasing heat would be to wreak far   
more serious and permanent damage  upon 
the moving parts than the broken rings  
or scored cylinders that  usually result
 from a lack of lubrication or cooling  
medium4    ,a large amount of the heat  
resulting from each explosion is carried
  out through the exhaust pipe in the   
form of the burned gases1 while  other  
portions radiate into the surrounding   
air4 ,these outlets are  not sufficient1
 however1 to carry away all the heat    
that is necessary  to enable the motor  
to run efficiently1 for proper piston   
lubrication  is exceedingly difficult to
 obtain at high temperatures4 ,there    
must1  therefore1 be more positive and  
direct means for carrying off this      
undesired heat1 and to accomplish this  
result every internal combustion  motor 
is provided with a cooling system of    
either the air or liquid  7usually      
water7 type4 ,motorcycle power plants   

and a few of the small  and medium-sized
 automobile engines employ the          
air-cooling system2 the  great majority 
of automobile engines1 stationary       
plants1 and marine  motors use water as 
the cooling medium4    ,let us consider 
first the air-cooled system4 ,the area  
presented  by the outside of a smooth   
cylinder is not large enough to enable  
sufficient radiation to take place4     
,that is1 the heat is concentrated  on a
 comparatively small surface1 and this  
is much more difficult to  keep cool    
than is the same amount of heat         
distributed over a greater  area--for   
the cylinder will be exposed to a larger
 quantity of fresh  air in the latter   
case4 ,therefore many air-cooled engines
 are provided  with a series of grooves 
and flanges on the outer surface of the 
cylinder4 ,the heat is conducted to all 
parts of this surface--flanges  as well 
as grooves--and the area of the surface 
that is exposed to the  cooling air is  
greatly increased thereby4    ,these    

grooves and flanges may extend          
circumferentially around the  cylinder1 
as is the case with many motorcycle     
engines1 or they may  extend            
longitudinally4 ,another form of        
air-cooling system consists of  pins or 
spines projecting radially from the     
surface of the cylinder4  ,the motion of
 the car through the air is generally   
sufficient to  create a circulation of  
the cooling medium1 but in order that   
this  circulation may continue while the
 car is at rest a high-speed fan  is    
provided that draws the air from the    
front toward the rear of the  motor4    
,this serves also to supplement the air 
circulation produced by  the motion of  
the car1 and keeps the motor much cooler
 than would be  the case were the       
machine run without the fan4 ,this fan  
is generally  attached to a bracket at  
the front of the motor1 and is driven   
either  by a belt or geared shaft4 ,in  
some designs1 however1 the fan blades   
are  included in the flywheel at the    

rear of the motor and the air is thus   
sucked over the cylinders4    ,one of   
the most effective air-cooling systems  
for use on an automobile  motor consists
 of the above-mentioned longitudinal    
flanges and grooves  enclosed in a thin 
jacket or casing surrounding each       
cylinder4  ,these jackets are open at   
the top and bottom of the cylinders1 and
  connect with large pipes1 or troughs1 
through which air is forced4  ,the      
trough into which the top of the jacket 
spaces open is connected  with the      
discharge end of a large fan4 ,the air  
is thus driven into  the top trough1    
through each jacket1 and into the lower 
trough1 the  farther termination of     
which is connected with the suction end 
of a fan included in the flywheel4 ,the 
two fans serve to set up a  rapid       
circulation of air which1 by means of   
the troughs and jackets1  is            
concentrated upon the surfaces of the   
grooves and flanges of  each cylinder   
and none is wasted on parts of the motor

 that it is  unnecessary to cool4       
,furthermore1 the rear cylinders receive
 as much  air as do the forward ones1   
for the trough serves to distribute the 
circulation equally along the grooves   
and flanges of each4    ,inasmuch as the
 heat from an air-cooled motor is       
radiated directly  into the current of  
air itself1 the surface is very         
susceptible to  temperature changes from
 the interior4 ,thus1 if the car is run 
for  a great distance on the low gear1  
and the cylinders become hot in         
consequence1 a larger amount of heat    
will immediately be radiated from  the  
cooling surfaces than is the case when  
the motor is running slowly4  ,a coast  
down a short hill1 however1 will serve  
to cool the motor  rapidly1 for if the  
engine is run from the momentum of the  
car with  the spark turned off1 cool air
 will be drawn into the cylinders1 and  
this1 in addition to the circulation of 
cold air on the outside1 will  reduce   
the temperature of the engine rapidly4  

,this is a feature of the  operation of 
an air-cooled motor that is not         
possessed to so large an  extent by     
those of the water-cooled type4    ,it  
is1 perhaps1 hardly accurate to apply   
the term water-cooled to  the ordinary  
type of automobile motor4 ,water is     
merely the medium  that transfers the   
heat from the cylinders to the cooling  
surface of  the radiator4 ,as air is    
used to cool this heated water1 we see  
that  the only difference between the   
two systems lies in the point of        
application of the actual heat-absorbing
 medium--which is air in both  cases4   
,thus in the air-cooled motor the air is
 carried directly to the  surfaces to be
 cooled2 while in the other type1 the   
heat is transferred  by means of the    
water to the point where it may be      
effectually  discharged into the air4   
,each cylinder of a water-cooled motor  
is surrounded by a space known  as the  
water jacket4 ,this space is generally  
cast with the cylinder1  although in    

some designs of motors the jackets are  
formed by the  subsequent application of
 a copper casing that serves to retain  
the  water4 ,the water jackets are      
connected with each other by means of   
piping and water-tight joints so that   
the water will pass successively  from  
one to the other4 ,if the water remained
 in these spaces1 it would  soon be     
warmed to a temperature far above the   
boiling point1 steam  would be formed1 a
 high pressure generated1 and infinite  
harm would  result--both to motor and to
 passengers4 ,the piping1 however1 does 
not  end with the connections between   
the cylinders1 but extends to and from  
the radiator4    ,this radiator is a    
large1 perforated structure placed      
either forward of  the motor to form the
 end of the bonnet-covering1 or in front
 of the  dash between it and the rear   
cylinder of the engine4 ,the radiator is
 a  mass of small cellular or tubular   
passages1 each one of which possesses   
an exceedingly large outer surface in   

proportion to the amount of water  that 
it can contain4 ,when the hot water     
reaches the radiator it is  distributed 
to these many cells or tubes1 and is    
thus spread over a  large cooling       
surface4 ,a large fan is usually located
 directly behind  the radiator1 and as  
this serves to draw the air rapidly     
through the  openings between the cells 
or tubes1 cooling is greatly            
facilitated4    ,there are several types
 of radiators in general use4 ,some     
consist of  a number of flat cells      
placed in such a manner that            
regular-shaped  air openings will be    
formed4 ,each side of each flat water   
cell abuts  on an air passage4 ,such a  
radiator is known as the honeycomb1 or  
cellular1 the former term being applied 
to those whose cells resemble  a        
honeycomb4 ,the tubular radiator        
consists of a number of vertical1       
parallel tubes through which the water  
passes1 and which are placed  a         
sufficient distance apart to provide    

ample air passages between  them4 ,each 
tube is covered at frequent intervals   
with fluted1 circular  flanges that     
serve to increase the radiating surface 
in much the same  manner as do the      
grooves and flanges on the cylinders of 
the air-cooled  motor4 ,all air passages
 in any radiator extend directly through
 the  width of the radiator1 while the  
water circulates from top to bottom in  
a vertical direction4    ,the reason for
 this circulation of the water will be  
apparent if we  call to mind a bit of   
our elementary physics4 ,when water is  
heated1 it  expands and rises1 and for  
this reason1 we always find the surface 
of  the water in a teakettle warmer than
 is that at the bottom--although  the   
latter is closer to the fire4 ,as the   
water is circulated through  the        
radiator1 it is cooled by the passage of
 the large amount of air  through the   
openings between the cells or tubes4    
,the water thus cooled  sinks to the    
bottom of the radiator and is replaced  

by the water  just heated by the motor4 
,the cooled water is conducted to the   
bottom  portion of the end cylinder1 and
 passes to the others in succession1    
gradually rising as it is heated1 until 
it is again forced to the  radiator at  
the top4    ,there are two methods of   
circulating the water through the       
cylinder  jackets and radiator4 ,the    
most common method consists of the      
introduction of a pump in the lower     
portion of the circulating  system4 ,in 
the case of automobile motors1 this pump
 is driven by  gears connected with the 
crank shaft of the engine4 ,such a pump 
will  be either of the gear or          
centrifugal type1 and will suck the     
cooled  water from the lower portion of 
the radiator1 and force it through the  
jackets4 ,the second method is known as 
the thermo-syphon system because  the   
circulation is automatic and depends    
upon the cooling of the water  in the   
radiator4 ,when the cooled water sinks1 
a syphon action is formed  that tends to

 draw the hot water from the cylinder   
jackets1 and the  automatic circulation 
will thus continue as long as the       
successive  heating and cooling take    
place4    ,inasmuch as the pump is      
driven by the crank shaft of the engine1
 its  speed will be proportional to that
 of the motor4 ,the same holds true  of 
the fan that serves to draw the air     
through the radiator4 ,it will  thus be 
seen that both the water and the air are
 forced at a more rapid  rate when the  
motor runs at high speed1 and that      
therefore the extra  heat generated by  
the more frequent explosions in the     
cylinders will be  counteracted to a    
certain extent4 ,the increased number of
 explosions  and the higher speed at    
which the fan turns also cause quicker  
heating  and cooling of the water by the
 thermo-syphon system1 thus forming a   
more rapid circulation4 ,inasmuch as the
 force exerted upon the water by  its   
cooling and heating is not as great as  
that formed by a high-speed  and        

efficient pump1 the pipes and           
connections of the thermo-syphon  system
 must be of ample size in order to keep 
the resistance to the  passage of the   
water as low as possible4 ,care must    
also be taken in the  design of this    
system so to construct and connect the  
pipes and jackets  that the hot water   
will be allowed to rise and the cool to 
descend1  and thus to make possible the 
syphon conditions on which principle the
  circulation is based4    ,the ability 
of the radiator to carry off the heat   
from the water  depends upon the        
rapidity with which the air passes      
through the  passages provided for the  
purpose4 ,the amount of air passing     
through  is determined by the speed of  
the suction fan and the rapidity of     
travel of the car itself against the    
wind4 ,it has been shown that1 when  the
 motor runs at a high number of         
revolutions1 the fan turns faster  and  
the rapidity of circulation is          
increased4 ,but if the car itself  does 

not increase its speed in proportion to 
the higher revolutions of  the motor1   
the maximum amount of air will not be   
forced through the  radiator passages1  
and the excess heat will not be carried 
off entirely  from the cylinders4 ,this 
is a condition that prevails when the   
motor  is run on low gear4 ,the speed of
 the motor is increased1 while that of  
the car is reduced2 additional heat is  
generated in the cylinders1 but  the    
speed of the air is not increased in    
proportion4 ,therefore a motor  that is 
driven a long distance on the low gear  
will have a tendency to  overheat4      
,water under atmospheric pressure cannot
 be brought to a temperature  above #bab
 degrees ,fahrenheit without being      
converted into steam4  ,therefore1 when 
the heat from a water-cooled motor      
cannot be carried  away sufficiently    
fast1 the water in the circulating      
system will begin  to boil4 ,as long as 
water remains in the jackets1 the       
temperature of  these spaces cannot well

 rise above #bab degrees1 and           
consequently there  is small danger that
 a water-cooled motor will become       
overheated to  the point at which the   
pistons will seize in the cylinders4    
,the  moment the water in the           
circulating system begins to boil1      
however1  exceedingly rapid evaporation 
naturally takes place1 and the water    
will  soon entirely disappear in the    
form of steam and vapor4 ,to run the    
motor under these conditions will mean  
that pistons and rings will soon  become
 stuck in their cylinders1 although     
liberal quantities of oil  will         
sometimes delay this inevitable result4 
,but even when the cooling water is not 
brought to the boiling point  there is a
 vapor that is constantly dispelled from
 it whenever its  temperature is brought
 above that of the air4 ,the water      
system of  an automobile must therefore 
be replenished at irregular intervals1  
depending upon the amount and nature of 
the running to which the car  has been  

subjected4 ,the older cars were provided
 with an extra water  tank1 generally   
located under the seat1 and connected   
directly with  the water jackets and the
 radiator4 ,the usual water-cooling     
system of  the present-day car1 however1
 is self-contained--that is1 there is no
  separate tank for the storage of the  
water4 ,the water is poured into  the   
top of the radiator1 and from this high 
point it reaches every part  of the     
circulating system4 ,whenever the       
radiator will accommodate a  couple of  
quarts1 or more1 it is well to fill it1 
for too much water  cannot be used on   
the modern design of cooling system4 ,it
 is true  that a motor runs at its      
highest efficiency when its temperature 
is  as great as that at which proper    
lubrication of the pistons can be       
obtained--for a gasoline engine is a    
heat engine1 and the greater  its       
unnecessary heat losses1 the less will  
be the power developed by  it4 ,but a   
motor cannot be kept at the proper      

temperature by reducing  the amount of  
cooling water in its circulating system4
 ,the best method  is to lessen the     
rapidity with which the water is cooled1
 and this  may be accomplished by       
placing a leather flap1 a cardboard1 or 
other  obstruction over a portion of the
 radiator to reduce the number of       
openings through which the air may pass4
 ,it should only be necessary  to do    
this in the coldest weather1 however1   
for the cooling system  of every motor  
is designed to maintain the proper      
temperature on all  except the hottest  
or coldest days4    ,it has been stated 
in a preceding paragraph that continued 
running on  the low gear is the most    
frequent cause of overheating a motor4  
,this  is true1 but it is not the only  
cause4 ,obstructions in the circulating 
system that reduce the flow of water    
will have this effect1 as will  also    
deposits on the interior of the         
cylinders that serve to prevent  the    
proper transfer of heat to the water in 

the jacket spaces4 ,removal  of the     
carbon will remedy the latter trouble1  
but to clear out the  circulating system
 is more or less of a complicated       
matter4 ,stoppage in  the pipes or      
radiator cells may be caused by a lime  
deposit from hard  water that may have  
been used in the circulating system4    
,there are  preparations intended to    
remove this deposit1 but such should not
 be  used without first advising with   
the maker of the car or an experienced  
repair man4 ,a series of battered cells 
in the radiator may reduce the  number  
of cooling spaces that should be        
traversed by the water1 and  thus the   
hot water cannot be distributed over as 
great an air area as  is necessary to   
maintain the motor at the proper        
temperature4 ,such a  condition will be 
apparent from a marked difference in    
temperature  between the affected       
portion of the radiator and the         
remainder4 ,if a  deposit has been      
formed on a certain series of cells1 or 

if they have  been obstructed in any    
other manner1 the hot water cannot      
circulate  through this section of the  
radiator1 and it will remain            
comparatively  cool4    ,water is a     
liquid that remains in its fluid stage  
only through a  temperature range of    
#ahj degrees--at atmospheric pressure4  
,at #bab  degrees it boils and turns to 
vapor1 while at #cb degrees it freezes  
and  becomes a solid4 ,in neither of    
these stages does it form a desirable   
cooling medium for a gasoline motor4 ,of
 the two1 however1 its solid  stage is  
the more harmful to the motor4 ,not only
 will it cease to  flow when it becomes 
ice1 but the expansion of the water     
during the  formation of the solid is   
liable to burst its retainer--whether it
 be  the cells of the radiator1 the     
pump1 pipes1 or even the cylinder walls 
themselves4 ,it is the radiator that is 
the most liable to suffer from  such a  
cause1 however1 for each cell contains  
so small an amount of  water that the   

liquid will be brought to the freezing  
point before the  larger volume in the  
jacket spaces approaches this           
temperature4 ,of  course the water will 
be kept well above the freezing point   
when the  motor is running1 and it is   
only when the machine has stood idle for
  several hours that care must be taken 
to prevent the formation of ice  in the 
circulating system4    ,aside from      
keeping the car in a warm place whenever
 the motor is to be  at rest more than  
two hours1 there is only one method of  
preventing  the cooling water from      
freezing1 and that is by the            
introduction of  some chemical that     
lowers the point at which the liquid    
will turn to a  solid4 ,there are       
several ingenious heaters available that
 are attached  to the circulating pipes 
and that serve to keep all of the jacket
 water  warm2 the use of these producing
 the same conditions as though the car  
were kept in an artificially-heated     
garage4    ,one of the most common      

liquids used in the cooling water to    
prevent  freezing is alcohol4 ,if equal 
parts of wood alcohol and water are used
  in the cooling system1 the resulting  
mixture will not freeze until  it       
reaches a temperature colder than #be   
degrees below zero4 ,a weaker           
mixture--one having #be per cent4 of    
wood alcohol--will freeze at  about     
zero1 and it therefore depends upon the 
prevailing cold-weather  temperature as 
to the proper proportion that should be 
used4 ,it must  be remembered that the  
boiling point of alcohol is much lower  
than is  that of water1 and that        
therefore a mixture that will not freeze
 in  exceedingly cold weather is liable 
to boil away on the first moderate  day 
on which the car is run4 ,the           
above-mentioned #ej per cent4 mixture   
of wood alcohol and water will boil at  
#ace degrees1 while the #be per  cent4  
solution will withstand a temperature   
#dj degrees higher before it  is        
transformed into vapor4 ,as the lower   

temperature will be reached  easily if  
the motor is run for some time in       
comparatively moderate  weather1 it will
 be seen that the stronger mixture      
should be used only  where winters are  
very severe4 ,it must also be borne in  
mind that1  as alcohol boils more       
readily than does water1 it follows that
 it  will evaporate more easily1 as     
well4 ,therefore1 in order to maintain  
a uniform proportion of wood alcohol to 
water1 the former should be  replenished
 more often than is the latter4         
,glycerine is another substance that is 
often mixed with the cooling  water to  
prevent the latter from freezing4 ,a #ej
 per cent4 mixture of  this and water   
has a freezing point of about zero1 or  
slightly lower1  and boils at           
practically the same temperature as     
water--#baj degrees4  ,combinations of  
wood alcohol and glycerine may be       
used--equal parts of  each being the    
usual proportion--and thus various      
freezing and boiling  points may be     

obtained4    ,the radiator is one of the
 most delicate parts of the motor car's 
construction1 and yet it is the most    
exposed to flying sticks and  stones    
that may be thrown up by the rapid      
travel of the car4 ,the  car owner may  
do well to follow the practice of many  
racing drivers  who place a heavy wire  
mesh screen in front of the radiator as 
a  protection against obstacles that may
 be struck by the front of the  car4 ,it
 would seem that sticks and stones would
 be thrown toward the  rear of the car1 
and would therefore avoid the radiator  
by a wide  margin1 but experience has   
proved that1 at high speed1 such loose  
pieces are frequently forced forward and
 are run into by the front of  the car4 
,,chapter ,,ix    ,,two-,,cycle ,,motors
      ,there has always been a strong   
prejudice in favor of the four-cycle    
motor for the power plant of the        
gasoline automobile4 ,this may be due   
to the fact that designers have spent   
most of their time and energy on  the   

development of this engine1 and that    
therefore the two-cycle type  has not   
yet been sufficiently tried out in the  
motor car to enable us  to judge fairly 
as to its real merits4 ,certain it is   
that in the few  instances in which the 
two-cycle motor has been used as an     
automobile  power plant1 the results    
have been highly satisfactory1 and the  
present  vogue of the four-cycle        
motor--with well over #ih per cent4 of  
the  automobiles now made adhering to   
this type--is largely due to popular    
prejudice in its favor4    ,as has been 
described in the first chapter of the   
present volume1  the four-cycle motor   
devotes a separate stroke to each of the
 events  of expansion1 scavenging or    
expulsion of the burned gases1 suction1 
and compression4 ,the two-cycle motor1  
on the other hand1 devotes but  two     
strokes to these four events1 and there 
is therefore an explosion  twice as     
often in the two-cycle engine cylinder  
as is the case with the  four-cycle     

type4 ,but in lieu of the suction stroke
 of the four-cycle  motor1 there must be
 some method of forcing the charge into 
the  cylinder of the two-cycle engine4  
,the base1 or compartment below the     
piston1 in which the crank revolves1 is 
used for this purpose4 ,as the  piston  
travels upward on its compression       
stroke1 a partial vacuum is  formed in  
the base1 and if a passage is opened    
between this compartment  and the       
carburetor1 the charge will be sucked   
in4    ,all outside connections with the
 base are tightly closed on the         
down-stroke of the piston1 and          
consequently the recently-inhaled charge
  will be compressed1 ready for its     
entrance into the cylinder above the    
piston as soon as the connecting passage
 is opened4 ,this passage is  opened1 as
 has already been described1 at the     
bottom of the stroke and  the compressed
 charge rushes in and fills the space in
 the cylinder  that at that time is     
being vacated by the exhaust gases4     

,the majority of two-cycle motors are   
made without any valve mechanism1  the  
opening and closing of the passages     
being entirely automatic4  ,these       
passages are cast with the engine and   
lead into the cylinder  through openings
 in the walls called ports4 ,the opening
 leading from  the cylinder to the      
exhaust pipe1 or exhaust port1 is placed
 near  the bottom of the stroke so that 
it is covered by the piston1 except  at 
the lower extremity of the travel of the
 latter4 ,just below the  exhaust port1 
and on the opposite side of the interior
 of the cylinder1  is placed the intake 
port1 or opening of the passage         
connecting the  cylinder with the base4 
,now1 as the piston is forced downward1 
it uncovers the exhaust port and  an    
easy means of escape is furnished for   
the burned gases4 ,immediately  after   
this1 the intake port on the opposite   
side is uncovered by the                
still-descending piston1 and the        
previously compressed charge1 which  is 

only awaiting the opportunity in the    
base1 blows in4 ,the exhaust  gases are 
still escaping when this happens1 and   
therefore it is  necessary to prevent   
the incoming charge from passing        
directly across  the top of the piston  
and out through the exhaust port before 
use has  been made of its explosive     
qualities4    ,consequently1 to keep it 
in its proper path1 a baffle plate is   
attached  to the top of the piston which
 serves to deflect the incoming charge  
toward the top of the cylinder1 and this
 not only prevents the loss of  the     
mixture1 but also furnishes a blast of  
air that helps to blow out  the burned  
gases4 ,on the return of the piston to  
the top of its stroke1  it first passes 
over the intake port and then covers the
 exhaust port1  effectually closing both
 and preventing the escape of the charge
 during  compression4 ,while this is    
going on1 it must be remembered1 the    
piston  is forming the partial vacuum in
 the base1 which serves to draw in the  

charge for the succeeding explosion4    
,if the charge is drawn directly into   
the base from the carburetor1 a  check  
valve must be used in the pipe          
connecting the two2 otherwise  the      
mixture would be forced back into the   
carburetor the instant the  piston began
 its descent4 ,a two-cycle motor drawing
 its charge in this  manner is known as 
the two-port type1 for there are only   
the exhaust  and the inlet ports in the 
interior of the cylinder walls4 ,the    
passage  connecting the carburetor with 
the base may enter at the bottom of the 
cylinder1 for this space and the base   
are the same when the piston is  at the 
top of its stroke4 ,thus if this port is
 placed so that it is  uncovered when   
the piston is at the top of its stroke1 
it will admit  the charge to the base at
 a time when a partial vacuum has been  
created  in this compartment by the     
upward movement of the piston4    ,this 
port is again covered as soon as the    
piston starts on its  downward journey1 

and thus the charge is prevented from   
escaping until  the intake port         
connecting the base with the top of the 
cylinder is  opened4 ,such a two-cycle  
motor is known as the three-port type1  
and  it will be seen that not even an   
automatic check valve is used in its    
passages--and it is consequently a      
valveless motor in the liberal          
interpretation of the term4    ,the high
 velocity of the charge recompenses for 
the short time that the  port is        
uncovered1 and consequently the base is 
filled with nearly as  large an amount  
of charge as is the case with the       
two-port motor--which  allows the       
incoming gases to enter the crank case  
during the entire  upward stroke of the 
piston4    ,it will thus be seen that   
the piston of the two-cycle motor acts  
as  a pump in two ways4 ,first1 the     
vacuum is formed that serves to draw    
the charge into the crank case1 or base1
 of the motor2 and second1  the return  
stroke of the piston compresses this    

recently-inhaled  charge and makes it   
ready to be shot up into the cylinder as
 soon  as the piston has uncovered the  
port that forms the upper terminal of   
the communicating passage4 ,there can1  
of course1 no greater amount of  fresh  
charge enter the cylinder than is drawn 
into the crank case4  ,consequently1 the
 amount to which the cylinder will be   
filled depends  upon the vacuum formed  
and the pressure exerted upon the charge
 by  the succeeding down-stroke of the  
piston4 ,it is to be supposed that  the 
piston rings will be tight and that none
 of the charge can escape  by them1 and 
therefore the vacuum formed and pressure
 exerted in the  crank case will depend 
entirely upon the displacement of the   
piston  in its travel compared with the 
total capacity of the crank case4 ,in   
other words1 if the crank case is large 
and the piston is small and  travels but
 a short distance1 its pump action on   
the entire volume will  be small4 ,but  
if the crank case is small and the      

travel of the piston  alternately       
doubles and halves the volume1 the      
motion of the piston  will cause the    
pressure in the crank case to vary      
greatly4    ,in a preceding paragraph it
 has been described in what manner the  
incoming charge in the two-cycle motor  
was used to scavenge the  cylinder1 or  
rid it of burned gases1 by deflecting   
the mixture and  allowing this to force 
out the remaining exhaust before the    
exhaust  port was closed by the upward  
motion of the piston4 ,it is evident    
that the greater the force1 within      
certain limits1 with which the  charge  
enters the cylinder1 the more perfect   
will be the scavenging  action4 ,but    
there is a limit to the pressure that   
can be attained by  the mixture when it 
is compressed in the crank case previous
 to its  discharge into the cylinder4   
,this limit is determined by the size   
of the space required for the revolution
 of the crank and big end  of the       
connecting rod1 and by the volume       

displaced by the motion of  the piston4 
,the crank must have room in which to   
revolve1 and the  displacement of the   
piston can only be the area of its top  
multiplied  by its length of stroke4    
,thus eight pounds per square inch is   
about  the usual limit of crank case    
compression with this type of two-cycle 
motor4 ,this may be varied slightly one 
way or the other by the  arrangement of 
the ports1 but it makes slight          
difference whether the  motor is of the 
two- or three-port type so far as this  
consideration is  concerned4            
,two-cycle motors have been designed    
which combine the principles of  action 
of both the two- and three-port types4  
,the most important  departure from the 
generally-accepted type of two-cycle    
motor1 however1  is the design in which 
the charge is fed into the cylinder from
 a  chamber that is absolutely          
independent of the crank case proper4   
,this  may be accomplished in several   
ways4 ,there may be what is termed a    

differential piston in which a separate 
plunger operates in the  interior of the
 hollow trunk piston1 and by means of   
the proper  connection with the crank   
shaft compresses the charge in the      
chamber  thus formed at the time it is  
to be forced into the cylinder4         
,another design for obtaining intake    
compression independent of the  crank   
case consists of a collar1 or circular  
enlargement at the base of  the piston4 
,this collar reciprocates within the    
lower portion of the  piston in a       
chamber which has been bored to the     
exact size4 ,the collar  consequently   
forms a variable base for this          
compartment1 and as the  piston         
descends1 the collar travels with it1   
thus drawing in a charge  of the fresh  
mixture4 ,on the upward stroke1 this    
mixture is compressed  by the collar as 
it reduces the size of the compartment4 
,it will be  seen that such a motor can 
be designed to compress the charge to   
almost  any amount4    ,inasmuch as the 

mixture1 as mentioned above1 is         
compressed on the  up-stroke of the     
piston1 it is evident that it cannot be 
discharged  into that particular        
cylinder at that time--for the mixture  
should be  delivered to its cylinder    
only when the piston is at the bottom of
  its stroke4 ,in the case of a         
four-cylinder engine1 however1 one of   
the pistons would be in the proper      
position for the entrance of the        
charge1 and it is into this cylinder1   
that the compressed mixture is  forced4 
,the compression space in each cylinder1
 therefore1 works for  its neighbor1    
rather than for itself4    ,this        
interchange of courtesies is obtained   
through the good offices of  a          
distributor in the form of a rotating1  
hollow cylinder having ports  cut       
throughout its length that register with
 corresponding passages  leading to the 
various cylinders4 ,this distributor is 
timed with the  crank shaft of the      
motor1 and may be driven either by a    

gear or by a  silent chain4 ,as the     
mixture is compressed in the separate   
chamber of  one cylinder1 the passage   
leading to the distributor is opened by 
the  revolution of the latter1 and the  
charge is led through this passage1  the
 distributor1 and thence through another
 passage--also opened by the            
distributor--to the proper cylinder4    
,the cylinders thus operate in  pairs1  
one receiving its charge while the other
 is about to begin its  explosion       
stroke--and vice versa4    ,the force of
 the explosion in a gasoline engine     
cylinder is not only  dependent upon the
 amount and nature of the inflammable   
mixture  admitted1 but upon the force   
with which it is compressed1 as well4   
,the average compression pressure of a  
two- or four-cycle engine of  the       
ordinary type1 is from #fj to #gj pounds
 per square inch4 ,inasmuch  as this    
pressure1 assuming that the rings and   
valves are tight1 is  proportional to   
the displacement of the piston stroke   

compared with the  volume of the        
clearance space1 the amount of          
compression is constant at  all speeds  
and loads of the motor4 ,should it be   
possible to increase  this compression  
at will1 it would be found that1 with a 
warm motor1 a  pressure in the          
neighborhood of #ajj pounds per square  
inch would serve  to generate sufficient
 heat to ignite the mixture before the  
formation  of the spark--for it is one  
of the elementary laws of physics that a
  gas will become heated when           
compressed4 ,it is for this reason that 
the  compression pressure of the        
ordinary automobile motor is kept in the
  neighborhood of #gj pounds per square 
inch4    ,a method of varying           
compression pressure to meet individual 
load  requirements has been devised for 
some motors1 however1 and while such    
types are not as yet in general use in  
automobiles1 it is probable that  the   
near future will find much advancement  
along these lines4 ,one such  two-cycle 

motor that has been designed especially 
for automobile use  employs a separate  
air compressor driven by the engine     
itself and used  as the clutch and      
variable speed transmission of the car4 
,the amount of  pressure generated in   
the compressor is dependent upon the    
resistance  offered to its              
operation--or1 in other words1 it       
increases with  additional load carried 
by the motor4 ,the compression1 or      
compressed  air1 rather1 is carried     
directly from the compressor to the     
cylinders  of the motor1 being admitted 
at the proper time by a rotary valve    
driven by the crank shaft4 ,thus the    
compression in each cylinder is         
automatically regulated by the load1 and
 a motor of this type possesses  a high 
overload capacity4    ,the motor        
mentioned above operates on somewhat the
 same principles as  those found in the 
,diesel engine1 which will be1 as many  
predict1 the  ultimate type of internal 
combustion motor4 ,the ,diesel motor is 

not  necessarily a particular make of   
engine1 but bears the name of the       
originator of the principles involved4  
,these are distinct from those  of the  
,otto cycle1 which is the principle upon
 which practically all  automobile      
motors operate4 ,the ,otto cycle        
consists of the well-known  series of   
events in the cylinder1 as follows3     
,ignition1 followed by the  explosion1  
or expansion of the burned charge2      
discharge of the exhaust  gases1 or     
scavenging2 admission of the fresh      
charge1 suction2 and  compression of the
 newly-received mixture previous to     
ignition and the  repetition of the     
cycle4 ,in speaking of the ,otto and    
,diesel engines1 it  must be borne in   
mind that they are referred to as a     
class1 rather than  as a particular     
make--as one would mention poppet valve 
or sleeve valve  engines--for there may 
be many manufacturers of each type4     
,although the ,diesel principle may be  
applied to either the two or  four-cycle

 type of motor1 it is to the former     
design that it lends  itself unusually  
well4 ,this motor operates a two-stage  
air compressor  in conjunction with a   
storage tank4 ,at the beginning of the  
compression  stroke1 pure air under high
 pressure is admitted to the cylinder4  
,in its upward travel1 the piston       
compresses this air to a pressure       
approximating #ejj pounds per square    
inch4 ,while it has been shown that     
such a pressure is about five times more
 than enough to generate  sufficient    
heat to cause premature ignition1 it    
must be remembered  that1 unlike the    
ordinary type of motor1 this is only    
pure air that is  injected into the     
cylinder and contains none of the       
explosive gasoline  vapor4 ,at the top  
of the stroke1 however1 when the        
compression is at  its maximum1 the fuel
 is injected directly into the cylinder 
without  having been previously         
vaporized4    ,this is another feature  
in which the ,diesel motor is entirely  

different  from the ,otto type1 for the 
latter must employ a carburetor to      
vaporize  the fuel before it can be     
admitted to the cylinder4 ,but inasmuch 
as  there is already a pressure         
approximating #ejj pounds per square    
inch  in the cylinder of the ,diesel    
motor at the time the fuel is injected1 
there must be a force behind the latter 
of #gej or #a1jjj pounds per  square    
inch in order to enable it to overcome  
the resistance of the  highly-compressed
 air in the cylinder4 ,in short1 the    
liquid fuel is  sprayed directly into   
the cylinder at a pressure of #gej or   
#a1jjj pounds  per square inch4 ,this   
tremendous pressure is sufficient1 not  
only to  vaporize the particles of fuel 
as soon as they enter the cylinder  from
 the nozzle1 or atomizer1 but to cause  
them to burst into  flame1 as well4 ,in 
other words1 the compression of the air 
previously  has generated sufficient    
heat in the cylinder to ignite the fuel 
immediately on its admission4    ,the   

fuel continues to be injected into the  
cylinder during the greater  part of the
 down-stroke of the piston4 ,in this    
respect1 also1 is the  ,diesel motor    
radically different from the ,otto type1
 for the latter  receives its full      
charge at one time and fires the entire 
amount in  a single explosion4 ,in the  
,diesel motor1 on the other hand1 the   
ignition continues as long as fuel is   
admitted1 and thus this engine  is of   
the internal combustion type in the     
strictest sense of the  word4 ,it is1   
after all1 the expansion of the gases   
due to the heat of  combustion that     
produces the power in a gasoline engine1
 and if the  fuel can be so admitted    
that it can burn during the greater part
 of the  stroke1 a high efficiency will 
be obtained4    ,the exhaust gases of   
the ordinary two-cycle motor pass out of
 the  exhaust port as it is uncovered by
 the descent of the piston4 ,those  that
 remain are forced out by the sudden    
admission of the fresh charge1  which is

 deflected upward and is intended to    
scavenge the top of the  cylinder4 ,but 
it is claimed that thus employing the   
fresh mixture as  a scavenging agent is 
wasteful of the fuel-permeated charge   
and does  not conduce to efficient      
running4 ,the system is simple in the   
extreme1  however1 and does its work    
well in small installations in which    
fuel  economy is not of vital           
importance4 ,but in the two-cycle       
,diesel type  of engine1 the high       
pressure of the pure air is used for    
scavenging1  and as this is admitted    
with so large an initial force1 the     
exhaust  port may remain uncovered for a
 longer period than would be the case   
were the air to rely entirely on the    
up-stroke of the piston for its         
compression4 ,then too1 whatever air may
 escape contains no fuel1 and           
consequently efficient scavenging may be
 obtained without waste4    ,at the high
 pressure at which the fuel is injected 
into the cylinder  of the ,diesel       

engine1 practically any grade of        
gasoline1 naphtha1  kerosene1 crude oil1
 or other form of petroleum can be      
vaporized4  ,the compressed air employed
 in the compression and injection of the
  fuel is also used for starting the    
motor1 for this is not a type that  is  
amenable to hand cranking4 ,thus the    
,diesel type of engine can be  run in   
any weather on any grade of oil fuel1   
and as the carburetor  and electrical   
ignition system are absolutely          
eliminated1 two of the  great sources of
 trouble of the automobile motor are    
absent--and this  feature1 alone1 even  
more than the superior economy of       
operation1 will  appeal to the average  
motorist4    ,just when this type of    
motor will be taken up by automobile    
designers  is difficult to state4 ,the  
,diesel type of engine has proved so    
wonderfully successful for large        
stationary power plants and for marine  
purposes1 and its reliability is so     
absolute on all grades of fuel1  that   

this motor may solve the                
failing-gasoline-supply problem4 ,as    
yet1  about #ajj horsepower is the      
smallest unit that has been made in any 
quantities1 but it was recently         
announced that this type would1 in  the 
very near future1 be built for motor    
trucks and other commercial  vehicles4  
,consequently1 it is well for all those 
interested in the  application of the   
two-cycle motor to the automobile to    
understand the  elementary principles on
 which this radically-different type    
operates4                99      99     
99      99      99      99              
,transcriber's note3    ,inconsistent   
hyphenation has been retained unless one
 form predominated4    ,the following   
corrections have been made3    p4 #ai   
,this give a much - give changed to     
gives    p4 #cd purpose of cleanning -  
cleanning changed to cleaning           
,everything else has been retained as   
printed4