Abstract: A lubricant supplying system for a DOHC type multicylinder internal combustion engine comprising a plurality of cylinders arranged in series in a cylinder block, a pair of cam shafts parallel to each other and rotatably supported by a cylinder head and cam holders fixed to the cylinder head at opposite sides of the respective cylinders along the cylinder arranging direction, a plurality of cams including low speed cams corresponding to intake and exhaust valves of the respective cylinders and fixed to the cam shafts, a plurality of rocker arms in slidable contact with the respective cams corresponding to the intake and exhaust valves of the respective cylinders, and a connection switching mechanism for switching connection and disconnection of the rocker arms in response to a hydraulic pressure to vary the operating states of the valves responsive to the operating state of the engine, wherein a hydraulic pressure supply passage independent from an oil supply passage for supplying a hydraulic pressure to the c

Abstract: A valve operating system for internal combustion engines comprises a free cam follower which is disposed between first and second drive cam followers operatively connected to engine valves and which is capable of becoming free relative to the engine valves, first and second guide holes respectively provided in the first and second drive cam followers with their axes corresponding to each other. The guide holes is opened to the free cam follower. A double open-ended guide hole is provided in the free cam follower in correspondence to the axes of the first and second guide holes. A first change-over pin is axially slidably received in the first guide hole and adapted to be fitted into the guide hole, and a second change-over pin is axially slidably received in said guide hole with one end thereof abutting against the first change-over pin, and is adapted to be fitted into said second guide hole.

Abstract: A drive cam follower operatively connected to an engine valve and a free cam follower capable of becoming free relative to the engine valve are adjacently disposed and adapted to impart in mutually different modes of operation in response to said engine valve rotation of a cam shaft. A connection change-over mechanism is provided between the cam followers and is capable of changing-over the interconnection and disconnection thereof, and resilient biasing means is provided between the free cam follower and the engine body for resiliently urging the free cam follower toward the cam shaft. The resilient biasing means comprises an urging piston slidably received in the engine body for abutment against the free cam follower, and a spring arrangement interposed between the urging piston and the engine body to resiliently bias the urging piston in a direction to abut against the free cam follower.

Abstract: A cylinder head for a water-cooled engine of the cross-flow type with the intake passages on one side and the exhaust passages on the other side and a central water jacket formed longitudinal down the middle of the head. Sprues are formed in the head casting to extend lateral across the head through the central water jacket to integrally join the walls forming the intake and exhaust passages. In a modification, a passageway is formed in a sprue to conducted exhaust gases from an exhaust passage to the intake side of the head for use in an exhaust gas recirculation system.