Glossary “valve seat” Definition:
Ring of hard metal to which the valve seals.

Glossary “valve seal” Definition:
Device placed on the valve stem or guide to prevent excess oil from seeping into the clearance between the valve stem and valve guide.

Glossary “valve rotator” Definition:
Device that rotates the valve while the engine is running. See positive valve rotators.

Glossary “valve retainer” Definition:
Term used for valve keeper or valve key.

Glossary “valve relief” Definition:
Term used for valve pocket. Small pockets cut into the piston crown to provide clearance for the valves.

Glossary “valve rack” Definition:
Holder that keeps valves in proper order when removed, to ensure proper reassembly.

Glossary “valve position sensor” Definition:
Sensor that relays information, in electronic form, to a process relative to the position of a valve.

Glossary “valve port” Definition:
Passage that allows the flow of intake or exhaust, into or out of the cylinder.

Glossary “valve pocket” Definition:
Area cut into the top of a piston to provide valve clearance.

Glossary “valve plate” Definition:
Plate containing suction and/or discharge valves located under the A/C compressor head(s).

Glossary “valve overlap” Definition:
The time that the closing of the exhaust valve overlaps the opening of the intake valve at the end of the exhaust stroke and at the beginning of the intake stroke, when the intake and exhaust valves are partially open at the same time depending on the spacing of the lobe centers on the camshaft and the cam’s duration.

Glossary “valve margin” Definition:
A small margin around the edge of the valve head between the valve head and the valve face. The margin adds strength and heat resistance to the valve.

Glossary “valve lifter foot” Definition:
End of a valve lifter that rides on the camshaft.

Glossary “valve lifter” Definition:
Cylindrically shaped hydraulic or mechanical device in the valve train that rides on the camshaft lobe to lift the valve off its seat by following the contoiur of the cam lobe(s).

Glossary “valve lift” Definition:
Distance that the valve moves from the closed to the open position.

Glossary “valve lash” Definition:
Specified clearance between a valve stem end and a rocker arm on an OHV engine or valve stem end and the camshaft on an OHC engine; necessary to allow for heat expansion.

Glossary “valve key” Definition:
Term used for valve keeper.

Glossary “valve keeper” Definition:
Small part that fits into the retainer groove located near the tip of the valve stem to secure the valve and valve spring.

Glossary “valve job” Definition:
Reconditioning of a cylinder head, including the valves.