New-York tribune., 1918-06-02
Automobile Fires--
How to Avoid Them
By William II. Stewart, Jr.

Chow did your car take fire?" "I
don't know. heard it pop back at the
carburetor and suddenly discovered
that it was on fire." "What made it
backfire ia the carburetor?" Again l
don't know. We can't find out because
the car is total loss"
This is no imaginary conversation,
because cars have burned in the past
and will again in the future due to
backfring in the carburetor.
The most frequent cause Is lean
mixture. This means more air in the
mixture than usual. The carburetor
gets out of adjustment in some way
and the mischief is done. A lean mix
ture is slow-burning. 1t burns all dur
ing the power stroke, all during the
exhaust stroke, and it is still burning
when the inlet valve opens, admitting
the fresh mixture. This takes fire and
the flame runs back to the carburetor.
If there is any gasolene dripping from
the carburetor heavy vapor is formed,
extending under the engine, where it is
held by the mud pan. The flame spreads
under the engine and soon reaches the
tank, melting the connections and re-
leasing a food of gasolene.
Lean mixture may be due to derange-
ment of the carburetor or leaky inlet
manifold. Spray nozzle too far closed,
auxiliary air valve spring too weak or
1yoI Iyn c%V nAn n1~ ~
are few carburetor causes. A leaky in
let manifold may be detected by running
the engine and injecting oil around the
joints. Oil will be sucked in at the
leak, where the bolts must be frightened
or new gasket installed in place Of
the leaky one.
Tho Rarer Troubles
We now come to trouble of the
inlet valve, which indeed are very rare.
The valve litter may be out of adjust
ment, leaving no clearance, or actually
pushing the valve off its seat If there
is little or no clearance the valve will
hold compression when the engine is
cold, but will leak when engine warns
up, due to lengthening of valve stem,
and OF course popping in the carbure-
tor occurs Immediately. Set the clear
ance at about two thicknesses of news
paper. Occasionally this valve may be-
come stuck, so that it cannot close.
This may be seen from the outside as
there will be an unusually large space
between the valve stem and litter.
Electrical troubles now engage our
attention. With single coil and dis
tributer system as is used on the
majority Of cars there would be some
distributor trouble or a short-circuit of
the distributor wires. See that all
wires are properly insulated and wipe
all dust from the distributor head. If
you know how to open the distributor
you should wipe out the inside occa-
sionally, using a cloth dipped in gaso-
line. This will remove all accumula-
tions Of dust, which will cause short
circuit If allowed to remain.
With the Fords
On Ford car we find the trouble
caused by short-circuits on the timer
wires. These chafe against each other
ana sometimes against the sides Of the
engine, wearing away the insulation
and so causing trouble. Close switch
using a battery, or run engine on mag
neto. and advance and retard the spark,
watching the commutator and wires. If
sparks are seen a short circuit is in
dicated which may easily be stopped
with tire tape.
Fortunately cars do not burn fire.
quently now as they used to, probably
because the fame is led away from the
carburetor by the hot air pipe leading
from the hot air stove on the exhaust
manifold. But don't think your car is
safe on that account. There are leaks in
these pipes and there is summer ad-
justment with large holes to let in air
when necessary. So watch out for
popping in the carburetor and deter
mine its cause Immediately. Here, as
elsewhere eternal vigilance is the
price Of safety"