Great Falls daily tribune., 1920-06-27
Barney 0ldfladd says:
SPARK PLUG TROUBLES

In the older days of motoring spark
plugs gave as much, if not more trouble
than any other part of the car. 1t was
common joke with motorists who had to
carry whole set of spares and then
some. to make sure they would get from
one place to another. Today this condi-
ton is reversed The spark is pretty
reliable piece of equipment when it is
made right, but sadly enough. there are
dozens of makes on the market not fit to
be put into an engine cylinder.
The ordinary form Of plug without any
fancy electrodes, if properly made, is as
much as anyone can ask. The greatest
trouble with plugs is directly traceable
to leakage in the plug, that is, hot gases
leak through the plug and heat the parts.
Many motorists think that the leakage
in the plug gives trouble because Of the
loss in compression, but if the truth
were known the power loss. due to the
drop in compression. is as nothing com
pared with the damage done by the heat
ing The hot gases cause insulators to
crack, cause rapid carbonization and all
the troubles that spark plugs give.
In many racing cars you will find the
plugs well cooled by water in the jack
cts. The part of the cylinder into which
the plug Is screwed is provided with
water space so the plug temperature will
be kept down. At the same time. drivers
use filmed plugs, that is, plugs fitted
with three or four cooling fins so that
further cooling may be had.
When you buy cheap plugs you get
cheap insulating material which will
crack or warp under the slightest leak
age. The workmanship is poor In these
plugs with the result that il gaskets are
used there usually is leakage of a slight
degree even when the plug is new. 1t
is easy enough to determine if there is
leakage. While the engine is running at
fair clip SQUIRT oil around the plug
joints and if little bubbles appear there
is leakage. 1t Is surprising how hot
plug will get because of even the slight
est leak The owner. if he finds such
plug, should either replace it, or dis
mantle it to find the cause.
Perhaps it is little dirt under a gas
ket. or a damaged insular, or perhaps it
isn't screwed into the cylinder well
enough.
The heating does more than warp and
crack parts. The gas that leaks through
the plug contains finely divided carbon
SCOT This deposits all over the plug
parts You probably noticed when you
dismantle plug that carbon appeared in
places where you little dreamed it could
get Carbon on the end of the insulator
forms a direct path for the current,
which then fails to jump the gap. Added
to this carbon deposit is that brought
about by the burning Of oil right on the
plug points.
All sorts of designs are offered to pre-
vent the formation of carbon and to
insure continuous plug operation. Nov
ing parts in plug are TO be avoided The
fact that the plug in demonstration does
all sorts Of apparently desirable things
is no reason at all that the plug will do
the same thing in a cylinder. Moving
part plugs may operate for a while, per-
to give service for half year and more
without even requiring so much as clean
| ing This assumes. of course. that fhe
engine is all right, that it is not pump
| ing oil in quantity and that the remand
er of the ignition system is functioning
properly.
In cleaning a spark plug to remove
carbon, immerse the plugs in kerosene
! for about Is minutes when removed the
carbon will be soft and can be scraped
or wiped off IF the plug can be taken
| apart this should be done.
| In order to operate satisfactorily the
gap must be neither too wide nor too
| narrow Usually 1-32 inch is allowed.
but this may vary slightly in different
| engines. If too wide it may not spark
at all, IL too narrow the spark may be
too weak and you get poor explosions.
Loose iEsulators may cause trouble. It
is easy to determine looseness Merely
grasp the part in the fingers and push
and pull it. Bad contact at terminals
causes much ignition troubles. The CON
nections to the plug must be clean and
tight and the cable insUlations must
show no cracks.