Schebler model "S" carburetor; points of adjustment.
wise gives a richened mixture). This adjustment is not sensitive
and can be turned from three to ten notches without seriously affecting
the idle.
The idle adjustment should be set so that by de-pressing the air
valve slightly (about 3 " to 3's") the engine will start
to cut out, showing that the idling mixture is about right.
If the mixture is too lean, the engine will stop when air valve
is depressed slightly.
If the mixture is too rich, the engine will speed up slightly on
depressing the air valve and the air valve will have to be depressed
considerably before the engine cuts out.
Important: If the idle adjustment is turned to the right (clockwise)
too far, the air valve will not seat, since the needle is shut
off too far. Turn to the left or (counter-clockwise) until air
valve seats and adjust as explained above.
Range adjustment: This adjustment is effective only in the driving
range at speeds from 20 to 40 miles an hour, and does not affect
acceleration or hill climbing with wide-open throttle, but does
affect the economy at driving speeds, and is intended to cover
but little more than the range for from maximum economy to maximum
powers. It will not affect the performance to any marked degree,
but will enable the intelligent driver to get the maximum out of
his car.
This adjustment as shipped from the factory will usually be found
to be the best unless it is necessary to give a lean or richened
mixture at speeds from 20 to 40 miles an hour.
Turning the range adjusting screw (B) to the left (counter-clockwise)
moves the fulcrum point (a) toward needle valve and gives the driving
range a lean mixture.
Turning it to the right (clockwise) so that more of the threads
of the screw (B) are exposed gives the driving range a richened
mixture.
To obtain the original setting as shipped from the factory, set
the end of the range adjustment screw (B) flush with the range
adjustment bushing (C).
If the range of adjustment is changed it is necessary to readjust
the idle mixture.
High-speed adjustment: This adjustment as shipped from the factory
ordinarily need not be changed. This adjustment is very sensitive
to one turn in either direction for the wide-open throttle position.
In changing this adjustment, try it on a hill after each change
for best results. In extreme cases it may be necessary to furnish
a leaner or richer mixture for wide-open throttle position.
The adjusting cam tappet screw (D) is turned to the left (counter-clockwise),
which moves the fulcrum point (a) toward the air valve to give
arichened mixture, and turned to the right (clockwise) to give
a leaner mixture.
To obtain the original setting as shipped from the factory, the
head of the range screw (B) should be flush with the range adjustment
bushing (C).
With throttle wide open adjust the cam tappet screw (D) until there
is about 3°2" to VI" space between the dash-control
lever (P) and the end of the range screw (B).
The accelerating pump: When the carburetor is ordered for a car
with which the factory is familiar, this adjustment will be made
at the factory. Other-wise the adjustment will have to be approximated.
This is possible, as great accuracy is not absolutely essential.
Too much gasoline is better than too little, since this makes better
performance possible with a cold engine, and the economy is not
affected appreciably.
In adjusting the accelerating pump, the method of procedure is
first to get the car up to running temperature, and then adjust
the size of hole (v).
If (v) is too small, the engine will not take hold immediately
when the throttle is suddenly opened at low speed. Therefore (v)
is enlarged until the softness is eliminated from the first few
explosions.
If the overflow hole (t) is too low, the engine will take hold,
then run soft, and then take hold 'again. The overflow is then
raised until the soft spot disappears entirely. The same manifold
will require continuously less accelerating gasoline as it gets
hotter. It has therefore been found advisable to make the hole
(v) larger and the overflow (t) a little higher than is absolutely
necessary on a hot manifold, taking care not to use so much gasoline
as to cause the engine to be heavy during acceleration when very
hot.
Explanation of the function of the dash-control lever: The model "S" has
no air choke. It delivers to the engine whatever air is required,
and meters the proper amount of gasoline into that air.
When a very rich mixture is needed, as in starting a cold engine,
the dash control lever (F) (Fig. 3) is pulled down by means of
the dash control wire (E). This raises the position of the needle
valve, and automatically supplies a very rich mixture to the engine;
thus enabling the engine to start easily.
This rich mixture, which is then being supplied to the engine,
is maintained at the proper ratio of gasoline and air for all speeds.
As the engine gradually warms up, the dash board control is gradually
pushed in; which in turn raises the dash control lever (F) and
adjusts the mixture to the different degrees of temperature of
the engine during the warming-up period, until finally, when the
engine has reached its running temperature, the dash-board control
is pushed entirely in, and the mixture of air and gasoline is again
back to normal.
Instructions for Starting
(1) Pull out steering or clash control; (2) retard spark; (3) open
throttle slightly; (4) turn on ignition
;4(5) push starter button.
As the engine warms up, the dash-control lever should be gradually
pushed in.
Float level: The correct float adjustment will permit the gasoline
to rise to approximately 1" below the top of the bowl. It
is unnecessary to check the float level with great accuracy, since
the carburetor is not sensitive to small fluctuations in float
level. Bend float arm lightly to adjust.
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