Abstract: A power driven remote control device is operable from a location remote from the engine for adjusting the length of stroke of one or more valves of an internal combustion engine during engine operation and while maintaining the valving cycle substantially unchanged. The strokes of all of the valves of the engine can be adjusted equal or preselected amounts concurrently. The control is arranged so that it can be installed on a conventional engine to provide an operating combination therewith without substantial modification of the existing engine structure. In this combination, the control utilizes fluid pressure generated by the engine, such as the oil pressure from the engine oil pump, for changing the length of valve strokes while isolating the valves from any rocking that might otherwise be imposed by the valve driving cam or tappet.