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Four On The Floor

A four-speed manual transmission with a floor-mounted shift lever.

Four Speed

A manual transmission with four forward gears.

Four Valves Per Cylinder

An engine that has two intake valves and two exhaust valves for each combustion chamber. While most engines have only one intake and one exhaust valve per cylinder, the 4-valve design allows for more efficient flow. Many 4-valve engines have dual overhead cams.

Four Wheeling

The off-highway travel in a four-wheel vehicle.

Four-barrel Carburetor

A carburetor having four ventures.

Four-bolt Mains

A main bearing cap that is held in place with four bolts.

Four-gas Analyzer

An exhaust-gas analyzer able to detect and measure exact amounts of hydrocarbons, carbon monoxide, carbon dioxide, and oxygen.

Four-point Seat Belt

A safety-belt system with two shoulder straps, two lap straps, and a single buckle.

Four-speed Transmission

A transmission providing four forward-gear ratios, one reverse ratio, and neutral, permitting closer matching of engine speed to load requirements than a three-speed transmission.

Four-stroke Cycle

1. A cycle of engine operation whereby the combustion occurs in every cylinder on every second revolution of the crankshaft. 2. A complete cycle includes intake or induction, compression, combustion or expansion, and exhaust. 3. Also known as four cycle.

Four-valve Head

A head design having four valves per cylinder.

Four-wheel Drift

A controlled four-wheel slide on a paved surface.

Four-wheel Drive

A vehicle having a driving axle in front and rear, so all four wheels are driven. Also 4WD.

Four-wheel Steering (4WS)

A system whereby all four wheels are used to steer a vehicle.

Four-wheel-drive

See 4-wheel-drive.

FP

Fuel pump.

FP-CKV

Fill pipe check valve.

FP-RV

Fill Pipe Rollover Valve.

FPCM

An acronym for Fuel Pump Control Module.

FPDM

Acronym for Front Passenger Door Module (GM).