Movable head engine

An internal combustion engine including a cylinder having means for the intake of fuel and air, means for the exhaust of combustion by-products, a reciprocable drive piston in said cylinder, a crankshaft, a connecting rod connecting said piston to said crankshaft, a camshaft, means for synchronizing the movement of the camshaft with the crankshaft, a single cam provided on said camshaft, a movable cylinder head piston reciprocally mounted in said cylinder in opposed relation to said drive piston, said movable head piston having separable upper and lower portions, and having a roller follower on each portion of said movable cylinder head piston, said roller followers being disposed within said movable cylinder head piston on opposite sides of the axis of rotation of said camshaft, movement of said camshaft in engagement with said roller followers causing reciprocating movement of said movable cylinder head piston wherein said movable cylinder head piston is projected toward said drive piston during at least and substantially for 45.degree. of camshaft rotation, is held at a point of maximum projection during at most and substantially for 135.degree. of camshaft rotation, is retracted during at least and substantially for 45.degree. of camshaft rotation, and is held at a point of maximum retraction during at most and substantially for 135.degree. of camshaft rotation.