The rocker cover, also known as the valve cover, is a component that sits atop the engine’s cylinder head, covering the rocker arms and valvetrain. Its primary function is to seal the top of the engine, preventing oil leaks and protecting the internal components from dirt, debris, and moisture. The rocker cover typically features a gasket or seal to ensure a tight fit and prevent oil leakage. It may also include provisions for ventilation or oil filler caps.