Service Procedures (Zenith 68)
Fuel Supply System (Zenith 68)
The 68 series carburetor is of the single barrel updraft design, with a single venturi, twin floats, and a semi-concentric fuel bowl to permit operation at quite extreme angles without flooding or starving the engine. It is of the “balanced” and “sealed” type since all air for fuel bowl ventilation and idle operation must enter through the air cleaner. The fuel supply system is made up of the threaded fuel inlet, fuel valve (needle and seat), float assembly and the float chamber. The idle system consists of two idle discharge holes, idle air passage, idle adjusting needle, idle jet, and fuel pick-up passage. The high speed (main metering) system consists of the venturi, main jet, main discharge, and well vent. Some models also include a main jet adjustment. The choke system is of the semi-automatic type and is made up of a choke plate, with a spring loaded poppet valve, mounted on a shaft located within the air intake and operated externally by a lever attached to the choke shaft.