ACCELERATING PUMPA device in the
carburetor that supplies an additional amount of
fuel, temporarily enriching the air-fuel mixture
when the throttle is suddenly opened
ACCELERATIONThe process of increasing
velocity. Average rate of change of increasing
velocity, usually in feet per second.
AIR BLEEDAn opening into a gasoline passage
through which air can pass (or bleed) into the
gasoline as it moves through the passage.
AIR CLEANERA device mounted on the engine
through which air must pass before entering the
combustion chamber. A filtering device in the air
cleaner removes dust and dirt particles from the air.
AIR-COOLED ENGINEAn engine cooled by air
circulating between cylinders and around cylinder
AIR FILTERA filter through which air passes, and
which removes dust and dirt particles from the air.
AIR-FUEL RATIOThe ratio between the volume of
air and the volume of fuel used to establish a
AIR-INJECTION SYSTEMA system which
injects air into the exhaust manifold or thermal
reactor so that the combustion of the carbon
monoxide and unburned hydrocarbons in the
exhaust gases can be completed.
AIR POLLUTIONContamination of the air by
natural and manufactured pollutants.
AIR PRESSUREAtmospheric pressure (14.7
pounds per square inch at sea level) or pressure of
air produced by pump, by compression in engine
cylinder, and so on.
ALLOYA mixture of two or metals, usually
produced to improve characteristics of the base
ANCHORED PISTON PINA stationary wrist pin
secured to the piston at the bosses that allows the
connecting rod to move about the pin.
ATDC After top dead center.
ANTIFREEZEA substance added to the liquid-
cooled engine to prevent freezing.
ANTIFRICTION BEARINGType of bearing in
which moving parts are in rolling contact; ball,
roller, or tapered roller bearing.
ANTIKNOCKRefers to substances that are added to
gasoline to decrease the tendency to knock when
the air-fuel mixture is compressed and ignited in the
ATOMIZATION The spraying of a liquid through a
nozzle so that the liquid is broken into tiny globules
AUTOMATIC CHOKEA choke that operates
automatically in accordance with certain
conditions, usually temperature and intake
BABBITAn antifriction metal lining used as a
wearing surface for bearing to reduce the friction
between moving components.
BACKFIRINGPre-explosion of air-fuel mixture so
mat explosion passes back around the opened
intake valve and flashes back through the intake
BACK PRESSUREThe resistance of gases to flow
through a system.
BAFFLEA plate or shield to divert the flow of liquid
BALL-CHECK VALVEA valve consisting of a ball
and seat. Fluid can pass in one direction only; it is
checked by the ball seating on the seat.
BBDCBefore bottom dead center.
BDCBottom dead center; the position of the piston
when it reaches the lower limit of travel in the
BEARINGA mechanical component that supports
and aligns the location of another rotating or sliding