Abstract: A carburetor has an induction passage, a fuel circuit and a choke valve positioned at the inlet of the induction passage. A metering rod extends transversely of the induction passage and has a variable diameter end portion projecting into an outlet of the fuel circuit. The metering rod is movable relative to the outlet in response to the choke valve opening and closing to control the quantity of fuel entering the induction passage. An opening force is exerted on the choke valve in response to the vacuum created in the engine, the exertion of this opening force being delayed until after an initial opening force has been exerted on the choke valve. The exertion of the second opening force moves the choke valve from a first position to a second and more fully open position.

Abstract: A staged carburetor has a body in which a pair of induction passages are formed, an inner passage having a venturi and an outer passage encircling the inner passage. A throttle valve positioned at the outlet of the pair of passages controls the flow of air through the passages. Fuel is delivered to the inner passage through a fuel circuit having an outlet at the venturi. A fuel metering rod extends transversely of the passages and has a variable diameter end portion projecting into the outlet. The metering rod is movable relative to the outlet to vary the quantity of fuel delivered. An air valve positioned in the outer passage normally closes the passage whereby air is initially drawn into the engine only through the inner passage. Increased demand for air by the engine results in opening of the air valve so air is drawn into the engine through both passages.

Abstract: An integral device for controlling the rate of throttle closure and for preventing after run of an internal combustion engine is provided which utilizes a pair of diaphragm assemblies for accomplishing both functional operations. The device includes a dash pot stem having an axial opening through it. The opening is operatively connected to a source of engine vacuum. A diaphragm housing defining a chamber has a pair of diaphragm assemblies positioned in it. A first diaphragm assembly is mounted to the dash pot stem. The second diaphragm assembly is movably mounted on the dash pot stem and includes a shaft extending through the housing. The shaft is engagable with suitable linkage means operatively connected to a throttle valve of a carburetor for the engine. Upon engine start, the application of engine vacuum to a first side of the first diaphragm operates on the diaphragm and housing so that, in effect, the housing moves in a first direction, positioning the shaft at its curb idle position.

Abstract: A carburetor is disclosed which includes a supplementary fuel/air supply circuit for bypassing a throttle valve to provide a fixed fuel/air idle mixture. The supplementary fuel/air supply circuit includes separate fuel and air passageways which join at a mixing intersection. The mixing intersection communicates with a main bore of the carburetor at a point below a throttle valve thereof. The supplementary fuel/air supply circuit also includes a piston valve, which is responsive to manifold vacuum, to control flow of air through the air passageway so that the air passageway is open during periods of high manifold vacuum but closed during periods of low manifold vacuum. An idle-mixture adjusting screw is provided for adjusting air flow through the air passageway; a piston-stop adjusting screw is provided for tuning the position of the piston valve at its "closed" position; and, in one embodiment, a special plug is provided for holding the piston valve in a piston chamber.