Abstract: In preferred embodiments, the pistons of a 4-stroke cycle diesel engine are provided with blowby storage chambers between two upper piston rings and a scavenging system to flush out blowby gases from the storage chambers when the pistons are at or near their bottom positions of piston motion. The scavenged blowby gas is recirculated to the engine induction system or may be conducted directly to the associated combustion chambers. The system reduces contamination of the engine lubricating oil with sooty particulates and other products in the blowby gases.

Abstract: Combustion chamber arrangements for divided chamber (prechamber) type diesel engines characterized by relatively low emissions of HC, CO and NO.sub.x, relatively low noise and physical stress and good fuel economy and power output and having (1) canted valves in the heads and forming therewith lateral wedge-shaped valve recesses, (2) cooperating wedge recesses in the pistons forming disc or pancake-like valve pockets in conjunction with the cylinder head recesses and (3) in-head prechambers closed by flame cups having wide connecting passages in their floors and side outlets for connection through channels with the edges of the valve pockets.

Abstract: Combustion chamber arrangements for divided chamber (prechamber) type diesel engines characterized by relatively low emissions of HC, CO and NO.sub.x, relatively low noise and physical stress and good fuel economy and power output and having (1) canted valves in the heads and forming therewith lateral wedge-shaped valve recesses, (2) cooperating wedge recesses in the pistons forming disc or pancake-like valve pockets in conjunction with the cylinder head recesses and (3) in-head prechambers closed by flame cups having wide connecting passages in their floors and side outlets for connection through channels with the edges of the valve pockets.

Abstract: An air valve, in the snorkel leading to the air cleaner in the induction system of an internal combustion engine, is actuated by a vacuum operated servo controlled by the depression in the snorkel to maintain a constant depression at the air cleaner. An exhaust gas recirculation control valve, operated by the air valve control servo, opens proportional to air valve opening to control exhaust gas flow into the induction system proportional to exhaust back pressure and air valve opening thereby providing exhaust gas recirculation flow proportional to engine load.