Friday, 10 May 2024, 12:52 PM
Site: IMI eLearning
Course: IMI eLearning (IMI eLearning)
Glossary: Automotive Glossary
V
Valve LagThe term applied to valves which remain open after the piston has passed tdc or bdc at the end of a stroke in the four stroke cycle. |
Valve LeadThe term applied to valves which open before the piston has passed tdc or bdc at the beginning of a stroke in the four stroke cycle. |
Valve LifterCam follower or tappet. |
Valve MarginThe thickness of the valve head between the valve face and the head surface. |
Valve NeedleThe control pin in, for example, a fuel injector. The needle works against an accurately shaped component to control flow. |
Valve OverlapThe term used to describe the angle of crankshaft rotation when the inlet and exhaust valves are both open. |
Valve SeatThe bevelled surface annular face in the cylinder head that closes each port and into which a valve seats and seals the port. |
Valve Seat InsertA steel insert fitted in aluminium and some iron cylinder heads to form a durable seating for the inlet and exhaust valves. |
Valve SpringThe spring that closes and holds closed the valve. It fits around the valve stem above the guide and between the cylinder head and valve spring retainer. |
Valve StemThe shaft of a valve. |