Abstract: A valve train layout for an overhead valve engine uses a single camshaft actuating two inlet valves and a single exhaust valve. The two inlet valves are preferably aligned on an inner side of a cylinder with the exhaust valve on an outer side. The inlet valves are preferably actuated by a cam follower and single push rod driving a rocker arm with dual arms and separate lash adjusters actuating the inlet valves. The exhaust valve is preferably actuated by a cam follower with a lash adjuster driving a single push rod operating a primary rocker arm that drives a secondary push rod pivoting an exhaust rocker arm to actuate the exhaust valve. In one embodiment, the primary rocker arm for the exhaust valve pivots on a common axis with the intake rocker arm. In an alternative embodiment, the primary rocker arm pivots on a canted pivot axis.

Abstract: A valve train for a twin cam engine has three valves per cylinder, including a pair of side-by-side intake valves and a single exhaust valve on an opposite, exhaust side of the combustion chamber. Dual camshafts in a V-type engine separately drive the intake and exhaust cams through a single dual arm intake rocker arm and a single exhaust rocker arm per cylinder, which provides much improved inlet port airflow for improved specific output compared to a single inlet valve engine. The single exhaust valve provides better catalytic converter performance due to lower exhaust heat loss than in four-valve engines of the same output capability. The intake and exhaust valve trains provide coplanar action of the push rods, rocker arms and valve stem axes, yielding an efficient and simplified valve train with a high flow combustion chamber. Additional features and advantages are disclosed.

Abstract: An engine assembly is disclosed which includes a cylinder block having cylinders, pistons disposed in the cylinders, and connecting rods connecting the pistons to a crankshaft. The crankshaft rotates to move the pistons reciprocally in the cylinders thereby inducing volumetric changes within the engine and, particularly between axially adjacent pistons. A crankcase disposed below the cylinder block has axial sidewalls extending therefrom to define a crankcase volume in which the crankshaft is disposed for rotation. Crankcase bulkheads extend laterally to connect the axial walls and define cylinder bays therebetween. Each of the crankcase bulkheads includes a crankshaft journal support and a surface configured to rotatably receive a complementary bearing cap for support of the crankshaft therebetween.