The rocker lever is a pivoting lever in the engine's valvetrain. It acts as a link between the camshaft and the engine valves. As the camshaft rotates, its lobes push on one end of the rocker lever, causing it to pivot and press down on the valve at the other end. This opens the valve at precisely the right moment to let air and fuel in or exhaust gases out. When the cam moves past, the rocker lever returns and the valve spring closes the valve.
