1942 - 1947 CHEVROLET SHOP MANUAL
Section 6 - Engine
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6-36 |
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The
throttle shaft end of the throttle connector rod fits through the throttle lever and is
retained by a hairpin lock at this point. The pump arm end of the rod is flattened and has a small
groove machined into it to
receive a lock. When the connector rod is assembled to the pump arm a
small coil spring fits over
the rod and is held in place by a stamped lock. This method of
attachment |
Starting
With the
choke valve in the closed position, as when starting a cold engine, suction from
the down stroke of the engine
piston draws a small amount of
air past the choke valve as shown in Fig. 74. This air is then mixed with
gasoline drawn from the main
nozzle and forms a rich mixture for easy starting. When the engine
starts the incoming rush of air
overcomes the choke shaft spring tension and opens the choke valve just the right amount
to maintain a running
mixture.
Idling
At idling speed the throttle is
closed. The suction from the down stroke of the engine piston is
concentrated on the idling port
below the throttle valve. This
suction is applied to the low speed passage in the carburetor body and results
in air being drawn in through
the bypass hole in the carburetor body. The air is then swept over
the top of the low speed jet,
causing gasoline to be lifted
from the jet. The gasoline and air mixture then passes through the economizer and down
the idle passage to the idling
ports where it is discharged into the throat of the carburetor
and then carried on through the
manifold to the cylinders. This operation is illustrated in Fig.
75. |
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Fig. 73—Carburetor Accelerator Pump Operation
provides a minimum of friction
while still providing an
anti-rattling device. |
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Fig. 75—Carburetor Operation During Idling
As the
throttle valve is opened the idling port above the throttle valve is uncovered and
further increases the suction on the idling system, permitting it to furnish the necessary fuel
mixture for the increase in engine speed. |
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Fig. 74—Carburetor Operation when Starling
Engine |
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