Abstract: In a drag racing vehicle, especially one utilizing a V-block engine, valve gap measurement and adjustment, valve spring force measurement, and the like are carried out with the aid of a foot-operated switch removably connectible to a circuit that carries battery current to the vehicle's starter motor. The foot switch is provided with a cable allowing it to be positioned in either side of the vehicle. Operation of the foot switch effects rotation of the engine crankshaft and camshaft through a small angle so that each valve can be brought to a fully closed condition for measurement or adjustment.