This valve tappet transmits the camshaft lobe motion to the pushrod, opening the intake or exhaust valve in the engine cylinder head. It sits between the camshaft and the pushrod in the valve train, converting rotational cam lift into linear movement. A worn tappet face produces a ticking noise and reduces valve lift, which lowers engine power and can cause uneven idle. The part is manufactured to the original geometry so the contact face matches the cam lobe profile without requiring shimming. On installation, verify the tappet rotates freely in its bore and apply assembly lubricant to the contact face before startup.