a number of embodiments of multiple valve internal combustion engines embodying a single camshaft for operating all of the multiple valves . the cylinder head is configured in such a way that it is reinforced across the center of the cylinder head by a bridging member and this bridging member can form a bearing surface for a center lobe of the camshaft . the camshaft is offset toward one side of the cylinder head and operates the valves through a plurality of rocker arms . in some embodiment , the rocker arms are journaled on a cam cover upon rocker arm shafts formed with reliefs aligned with openings in the cam cover for passing components such as a spark plug or a fastener for securing the cam cover to the cylinder head . both single and multiple cylinder embodiments are disclosed .