Section 6 - Engine

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
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.
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.
Fig. 73—Carburetor Accelerator Pump Operation
provides a minimum of friction while still pro­viding an anti-rattling device.
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.
Fig. 74—Carburetor Operation when Starling Engine





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