What are they?

An engine's valves are the metallic elements that allow the fuel-air mixture to enter the combustion chambers and the gases produced by its explosion to escape. Without these mechanical elements, the engine would not function properly, as their movement is vital to producing the energy needed to drive the wheels.

Structurally, a valve consists of a long section called the stem or tail of the valve (commonly known as the valve stem) and another upper section called the head (the valve plate or valve head). Alloy materials are used in their manufacture because they must withstand high temperatures during their operating cycle (up to 1000°C).

Function:

Their actual function is very basic and simple. They are responsible for managing the entry of fuel and air (fuel-air mixture) into the cylinder. After the mixture explodes due to the compression of the piston, they allow the gases resulting from this explosion to escape.

Technically, they are located in the cylinder head (commonly known as the cylinder head). The wide part (the valve head) rests on the head, fitting snugly to properly seal the cylinder. The lower part, or stem, sits inside the guide and merely completes the opening and closing motion commanded by the camshaft and springs.