Abstract: An internal combustion engine in which the combustion chamber volume is reduced during the movement of the power piston in its compression and power stroke. This permits delaying the time or maximum combustion pressure, due to the ignition and expansion of the compressed fuel/air charge, until the power piston is well past top dead center (TDC), 35 degrees after TDC for example. One advantage to this mode of operation is that the engine crankshaft journal has moved to a position where the axis of the journal is more offset, compared to at or near TDC, from the axis of rotation of the crankshaft so engine torque is increased. This is accomplished by a pair of half round valving pistons mounted in a bore in the cylinder head. The axis of the cylinder head bore coincides with the axis of the engine block bore in which the power piston moves. A camshaft assembly mounted in the cylinder head includes cam discs that are connected to the valving pistons.