Richmond times-dispatch. [volume] (Richmond, Va.) 1914-current, 1917-12-02
LESSONS ON
PROPER CARE OF AUTOS
arSe Proportion of Missing and IT.
regular Running Of Engine Due
to Faulty Spark Plug.
EST WILL REVEAL TROUBLE
'ccided Economy to Buy the Best,
Which Will Often last for From
10000 to 10000 Miles, While
Cheap One May Not Last 1000.
LESSON NO. OF.
The Snnrk Plug.


Fid irregular running Of the auto en-
| t'hc is due to Il faulty spark plug. Tho
/ SStioh or the engine, when there Is Il
t'uity spark plug, is. however. very
i ftnliar 10 the action when there IL loss
| compression in one cylinder. y
! Psi only will tell which is at fault.
J In studying the faults OF spark
pug. let US first see what it's action
! + ana how the spark is formed
In the illustration \ Is the body
II the plug. which is screwed into the
| CYLINDER OF the engine. and so makes
In excellent electrical contact Chat is.
passage for the electrical currently,
Elth 1t. u is OF nonconductirs ma
| Frial, through which the current can
1 got 80 from the rod 70 the body OF
| Pc plug. G. is Il rod to which the cleo
| bic wire is attached. and is called an
I Eectrode, while IL. also called an cleo
Eode. Is Il heavy wire attached to the
Eody Of the plug. The space between
Fie electrodes. J. is called the spark
Eap.
You were told previously that the
| Sow OF an electric current can be COM
l cared TO the flow of water, the two
tct!ng very much the same, and to
hrge extent following the same laws
nature. Thus, it requires pres
i Pure (called voltage) TO make cleo
Eicity flow through wire just as 1t
! ' Ess. to make water flo" through
/ study for 4 moment Figure .. Here
Eatcr could flow through the passages
E. y. y. were IL not for the small
eorton w Of the containing material
sf, however. the material Of which w
Il made were not very strong. then il
Ehc pressure OF the water We're greatly
eaised, eventually this pressure would
&c so great as to cause the material
kf w TO crack. and so the water would
burst through.
~, II w were made thicker. 1t would
| Ieaulre a much higher pressure for
The water to burst through. This
Eould also be true II the material were
[Etrongcr.
Again. IL the containing material
i Some point. say u. were to develop
crack or weakness of some sort, so
Is TO be weaker At this point than the
faterial at W, then the water would
eurst through at this point before Il,
you'd burst through ut W.
Compare nov Figures i and .. Does
pot the air space around T. in Figure
air is nonconductor Of electricity
End the Insulation of this wire. the
*orcelain ID Of the plug, and the air
. around the bottom If the electrodes
below tho porcelain appear to mako
passage for The electric current
| through +. and u. just as the ma
. Ierial OF Figure makes the passage
III. y and for the water and will
bot The flow OF the electric current
be stopped hy the air OF the gap Z
lust us the flow OF the water is stop
| ped by the material of W. Likewise
he current VIII burst through the air
bpacc' or air gap. ii the pressure Cor
fo!tase) is high enough. just AS the
lvatcr vii! hurs, through w.
Now, when the electricity bursts
Through an air gap. hot spark Will
Ne generated and the cracking Of the
3s.ir can be distinctly heard. You have
9pftcn seen this action during a thun-
Her storm. The electricity which has
i gathered on the clouds tries to flow
Prom one to the other. and Is prevent
led by the air between, but as the
tlouds come closer together, the air
becomes thinner and too weak to resist
b. and so the electricity bursts through
giving out the spark, lightning" and
| fou hear the cracking" OF the air, in
he thunder.
Thus We see that hen current of
I high voltage tprcssurc) electricity is
!fcnt through the wire + 10 the spark
8hlug, IL Will pass through the electrodc
~ and then jump the air gap h, giving
The required spark as 1t does SO.
Let us see what troubles" the spark
I!plug is subject to. First OF all we
binow that IL required a high voltage
ITO make the current jump the gap.
INs the voltage of Il magnetic or gene
! rator is dependent upon the speed OF
PTS armaturc, but Il comparatively low
voltage is generated when the engine
Ms being crankcd, which voltage is Of
ken too low TO give Il spark Thus,
3with many systems OF ignition, and es-
+hecially those on a big and hard-to
crank engine, Il battery must be fur
ished III addition to the magnetic,
! Mile in many smaller engines it is
Lpiten necessary 10 vigorously spin the
3crank before the engine Will start.
The greater the air gap the greater
will have TO be the voltage and If the
gap is too great the voltage will not be
ihgh enough TO give a spark. Here. too.
HIS one OF the reasons why an engine
Twill often run perfectly at high speed
land miss at the lower speed. we have
seen that II lower voltage is generated
lat low speed than high. so when the
1gap is a little too great. there will be
In spark at high speed and none at
Now, about 80 Of inch is the cor
| sect distance apart for the points
AS the kind of material will affect
1.-The pressure required for the water
ITO burst through, so the condition of
Itne air Of e." about the spark plug
3po!nts WI; affect the voltage re-
L hurried 1t takes a higher voltage 10
HUMP a3:pss n compressed mixture
lof gas and air than il does to jump
N,cross pure air. Thus there will be n
s.aiss, when the points are Il little too
ifar apart. and the car is ascending
Ia hill with the throttle wide open, as
under this condition the compression
Twill he high
This Ohc condition of the gas
affecting the spark) teaches another
that II is wise to
carefully watch the distance OF the
spark plug points. especially in winter.
when starting in cold weather it is
GENERALLY necessary to make the mix
iture very rich. and should the points
bio n little too far apart there will be
kno spark In the cylinder. even though
Tho usual spark tests would Indicate
lone. Closing the points a little will
Ioften facilitate starting.
AS the containing material OF Figure
|2 will allow the water To escape be-
1foro it breaks through w, in case of
h crack or weakness in it. so will the
electric current escape across the por-
|cclain OF the plug in case of crack,
Tor it's being coated with carbon or oil,
before 1t can jump the gap. In this
~ ha