under pressure unseats the discharge valve and fuel flows into the pump discharge passages where it is discharged into the main air stream beside the booster venturi. The pump discharge nozzle is a calibrated restriction that meters the proper amount of fuel.
The pump inlet check valve prevents a reverse flow of fuel into the fuel bowl when accelerating pump piston is depressed. The pump discharge needle valve prevents the siphoning of fuel from the accelerating pump well at high speeds; and the filling of the pump cylinder with air on the upward stroke of the piston.
CODE - FUEL
ACCELERATING PUMP SYSTEM
4. MAIN METERING SYSTEM
At constant cruising speedunder normalload conditions the main metering system supplies all the fuel required by the engine.
MAIN METERING SYSTEM
CODE
Fuel flows from the float chamber through the main metering jets into the main wells. Air is introduced to fuel flowing up in the main well by air bleeds in the walls of the main well tubes. As the fuel-air mixture passes from the main well to the main discharge nozzle, additional air is introduced to the mixture by the aspirating nozzle. The mixture is then discharged into the air stream at the booster venturi in response to the vacuum produced by the air flow through the carburetor.
POWER ENRICHMENT SYSTEM
5. POWER ENRICHMENT SYSTEM
The extra fuel needed to enrich the mixture for high power operation is supplied by the fully automatic vacuum operated power enrichment system.
A spring-loaded piston and stem assembly