Abstract: An engine crankcase ventilation system has internal crankcase vapor recirculation passages including a cavity in a valve cover arranged for push-in mounting of a PCV valve in the vapor flow path and a screw cap closing the cavity through which the PCV valve is installed or removed. The screw cap preferably includes finger-like abutments to maintain the PCV valve in position against the differential pressure of crankcase vapors across the valve.

Abstract: The intake manifold of an internal combustion engine has incorporated therein a bottom mixture plenum in heat transfer relationship for heating thereof by exhaust gases discharged from the engine. The plenum receives the induction mixture for the engine through at least one inlet bore in the form of a tube perforated through its side wall to distribute air and crankcase ventilation fumes from an air chamber located directly under the carburetor pad of the intake manifold and to distribute recirculated exhaust gases from a second chamber positioned between the plenum and the air chamber, the second chamber being supplied with exhaust gases for recirculation, the air chamber providing, in effect, an air gap insulator to reduce the transfer of heat from the exhaust gases to a carburetor mounted on the conventional carburetor pad of the intake manifold.

Abstract: A vehicle mounted internal combustion engine has a dual exhaust system including a single manifold having separate plenums connected to receive exhaust from diverse ones of the engine cylinders. The plenums have separate concentrically arranged discharge fittings which connect with a pair of exhaust pipes, mounted one inside the other, to provide two separate exhaust flow paths from the engine cylinders to the ends of the manifold connected exhaust pipes at their juncture with an associated exhaust converter.

Abstract: In an engine fuel system including a carburetor, a liquid fuel tank and a fuel vapor reservoir for the storage of fuel evaporated from the liquid fuel tank, a conduit is provided between the fuel vapor reservoir and carburetor induction passage to supply fuel vapor from the fuel vapor reservoir to the engine for combustion during engine operation. The carburetor is set for an air-fuel ratio leaner than stoichiometric; and a valve is provided in the conduit to control the flow of fuel vapor therethrough in accordance with the output signal of a zirconia sensor in the engine exhaust in closed loop control to maintain a constant air-fuel ratio near stoichiometric. An air inlet is provided in the fuel vapor reservoir to ensure a continual rich mixture of fuel vapor and air therefrom during engine operation.