Camshafts main parts are lobes. When the camshaft spins, the lobes open and close the intake and exhaust valves in time with the motion of the piston. The shape of the cam lobes and the engine perform simultaneously in different speed ranges. A camshaft is a shaft to which a cam is fastened or of which a cam forms an integral part. The camshaft is used to operate poppet valves. It then consists of a cylinder rod running the length of the cylinder bank with a number of lobes protruding from it, one for each valve. Camshaft Only Will be tested to ensure it is true before shipping Lifters Rocker arms Pistons A shaft mounted inside the engine that controls the valve timing. On "V" type engines, the camshaft is most often mounted inside the engine block between the cylinders. On inline engines, the camshaft may be either inside the block or in the cylinder head.