Evening star., 1925-11-15
By WILLIAM UIILMAN.

New problems in car design come
and go. unexpected troubles develop
and are solved, but the problem Of
carhuretion continues as motordonS )
biggest puzzle.
1t has uaffied automotive engineers
as wea as car owners, largely be-
cause the factors affecting carbure-
ton will not stay out. Frequent
cha nges in engine design, increase
in the number of cylinders, shifting
Of their arrangement. varying grades
of ga soline, increa sed range Of speed
AL have contributed toward perpetual
Ing the carburetor as the cars CHIEF
enigma.
Much carburetion trouble has been
traced to an excessive USE Of the
intake manifold for operation Of &C.
cessories. The intake manifold often
is tapped Tor a windshield wiper. a
valve-oilins device. the vacuum tank,
an oil purifier or primer. With
several OF these devices going at tho
same time considerable suction Is d.
verted from the carburetor so that
an insufficient amount of gas Is fed
through the low speed jet while the
engine is ldIing or running slowly.
Leaks Cause Trouble.
Aside from the diversion of the sue
huretion. the situation may be COM
plicated further by a leaky connec-
ton in one or more Of these devices
so that no adjustment OF the carbu-
rotor could possibly compensate for
the condition. The car owner Is con.
fronted by the sort of trouble he
would experience with a manifold
gaSket leak.
Such extremes are becoming rather
who are trying TO overcome time
honored difficulties. such as popping
back in cold weather starting, are
hopinc that motorists will refrain from
adding TO the number OF Carburetor
troubles. Many motorists nowadays
drive so far in a single day that the
Carburetor encounters Winter and
Summer conditions without q change
in the adjustments. Drivers also 60
from low grade to high test gasoline
and then complain because their cars
fail to pull steep grades.
The car makers themselves are not
out Of the dark with respect to car.
buretion, although they are making
rapid progress in that direction. A
popular straight-eight model, recently
put on the market, failed to run
smoothly in high gear at low speed.
Certain changes in the carburetors OF
these cars were made, but without the
desired effect. The factory changed
even running continued. The trouble
finally was traced to the valves and
proper adjustment made.
A number of engines of the six
cylinder type are not fed properly.
Several of the cylinders get more than
their share of fuel. while others are
underfed. due to improper carburetion.
Until the early part OF this year one
Of the most highly regarded OF AmeH-
can cars had a habit Of popping or
backfiring through the carburetor
down from high speed. 1t was q
carburetion problem. but 1t has been
corrected.
Remedy Became Problem.
Not long ago on. OF the chief difh-
culties In Carburetton was to supply an
extra charge OF gas at the moment OF
accelera ton. Engines normally were
sluggish a nd the csrburetors were not
designed to make any compensation
for this shortcoming. One Of the lead
ing carburetor manufacturers, how
ever, devised what is known as an
accelerating well, so called because II
built up a reserve of raw gasoline
which was released and allowed 70
pass into the mixing chamber through
the high speed jet when the throttle
was opened. 1t solved the acceleration
problem. but was soon to become a
problem in tsef.
Some one conceived the idea of the
hot spot" and the trouble started.
This allows the hot exhaust gases TO
come into direct contact With the out
side nf the intake ms nifold at some
stra tegic point go as 10 preheat the
gas on it's way to the cylinders. 1t
is an excellent idea and one that
makes possible quick warming up,
economy and high speed. but. com
.hined with the accelerating well of
carhrWetor. il causes bucking and jerk
ing At speeds of from IL to 20 miles
an hour. The engine gets too rich q
miXturo upon accelera tion, and the
RENEE les in rendering the accelerat-
Ing : Il less effective and in making
he carburetion uniform throughout
the entire range Of the engines speed.
Slight changes in engine design often