BIMETALReferring to the thermostatic bimetal
element made up of two different metals with
different heat expansion rates; temperature change
produces a bending or distorting movement.
BLOCKSee CYLINDER BLOCK
BLOW-BYLeakage of the compressed air-fuel
mixture or burned gases from combustion, passing
piston and rings, and into the crankcase.
BLOWERA mechanical device for compressing and
delivering air to the engine at higher than
BOILING POINTThe temperature at which a liquid
BOOST PRESSUREThe pressure in the intake
manifold while the turbocharger is operating.
BOREThe diameter of a cylinder. Also used to
describe the process of enlarging or accurately
refinishing an engine cylinder.
BRAKE HORSEPOWERThe power actually
delivered by the engine that is available for driving
BTDCBefore top dead center.
BUSHINGA replaceable lining for a hole in which a
shaft, rod, or similar part moves.
BUTTERFLYThe choke or throttle valve.
BYPASSA separate passage that permits a liquid to
take a path other than that normally used.
CALIBRATION (l) Balancing: The setting of the
delivery of an injection system or the setting of the
rack pointer on a single unit pump in relation to
predetermined positions of a quantity control
member. (2) Adjustment: Fixing fuel delivery and
speed adjustments to specified engine
CAM-GROUNDA process by which the piston is
ground slightly egg-shaped and, when heat
CAMSHAFT The shaft in an engine that has a series
of cam lobes for operating the valve mechanism.
CAMSHAFT PUMPAn injection pump containing
a camshaft to operate the pumping element or
CARBONA substance deposited on engine parts by
the combustion of fuel. Carbon forms on pistons,
rings, valves, and so on, inhibiting their action.
CARBON DIOXIDEA gas resulting from burning
CARBON MONOXIDEA colorless, odorless,
tasteless, deadly gas found in engine exhaust,
formed by incomplete burning of hydrocarbons.
CARBURETION The action that takes place in the
carburetor: converting liquid fuel to vapor and
mixing it with air to form a combustible mixture.
CARBURETOR The device in a gasoline fuel
system that mixes air and fuel and delivers the
combustible mixture to the intake manifold.
CATALYTIC CONVERTERA device used on the
exhaust system of gasoline engines to reduce
CETANEIgnition quality of diesel fuel. A high-
cetane fuel ignites more easily (at lower
temperature) than a low-cetane fuel.
CFMCubic feet per minute.
CHOKEA device in the carburetor that chokes off,
or reduces, the flow of air into the intake manifold;
producing a partial vacuum in the intake manifold
and a consequent richer air-fuel mixture.
CIDCubic inch displacement.
CLOSED CRANKCASE VENTILATING
SYSTEMA system in which the crankcase
vapors are discharged into the engine intake system
and pass through the engine cylinders rather than
being discharged into the air.
CLOSED NOZZLEA nozzle incorporating either a
poppet valve or a needle valve, loaded in order to
open at some predetermined pressure.
COMBUSTION The rapid burning of the air-fuel
mixture in the cylinder.
COMBUSTION CHAMBERThe space at the top
of the cylinder and in the head where combustion of
the air-fuel mixture takes place.
COMPRESSION The act of pressing into a smaller
space or reducing in size or volume by pressure.
COMPRESSION RATIOThe ratio between the
volume in the cylinder with the piston at bottom
dead center and with the piston at top dead center.