An engine valve, also known as a poppet valve, is a mechanical device that controls the flow of gases (air and fuel mixture or exhaust gases) into and out of the combustion chambers of an internal combustion engine. The engine valve consists of a cylindrical shaft, often referred to as a valve stem, with a head on one end. The head of the valve, typically circular or oval, is designed to seal against a valve seat, forming a tight closure when the valve is closed. When the valve opens, it creates a passage for the gases to enter or exit the combustion chamber.
