Genuine OEM Ford Valve Spring, part number 1099933. This spring's function is to close the engine valves after they have been opened by the camshaft, playing a vital role in the engine's combustion cycle. It is a component of the engine's valve train. Made from high-tensile spring steel to withstand repeated compression and maintain its integrity. Genuine OEM valve springs are precisely engineered for the correct spring rate and fatigue resistance.