Abstract: A diaphragm-controlled carburetor which includes a diaphragm positioned in a chamber and dividing the chamber into wet and dry chamber sides. A valve is positioned in the wet chamber side, and is responsive to the diaphragm for feeding fuel to fuel jets and thence to a fuel/air passage. The dry chamber side is connected to receive pressure pulses from the engine crankcase through a three-position valve. The valve has orifices selectively interconnected by a rotatable valve disc for feeding pulses at first intensity to provide an enriched fuel/air mixture for starting, at a second lesser intensity to provide a less enriched fuel-air mixture for engine warm-up, and to block pressure pulses from the dry side of the control diaphragm.

Abstract: A retainer for plastic carburetors which eliminates the necessity for mating flanges bolted together and thus avoids distortion of the body due to clamping pressures. The carburetor body has male parts which insert into recesses in an engine block or heat dam to seal in relation thereto and a forked clamp embraces a necked portion of the carburetor body and is clamped in cantilever fashion so that the plastic body is retained securely without distortive forces.