Fuel enters the carburetor through the fuel inlet channel located in the air horn. A needle valve and seat regulates the quantity of fuel flowing into the fuel bowl located in the main body. The fuel level within the carburetor is maintained at a predetermined level by a dual pontoon float and lever assembly, which controls the movement of the needle valve. The float reacts to any lowering in the fuel level. The needle, riding on the float lever, falls away from the seat as the float drops to the lower fuel level.

To prevent fuel starvation during hot fuel vapor handling an auxiliary fuel inlet valve opens to supplement the main fuel inlet valve. The auxiliary valve opens when the float drops below a predetermined level. The float lever presses against the auxiliary valve plunger, opening the valve for addtional fuel to enter the bowl. A mechanically-actuated valve vents the fuel bowl externally during periods of idle and part throttle operation, when fuel vapor is most likely to form. The accelerator pump link controls the movement of the external vent valve.