TORQUE CONTROLA device which modifies the
maximum amount of fuel injected into the engine
cylinders at speeds below rated speed to obtain the
desired torque output.
TURBOCHARGERAn exhaust driven compressor
that forces air into the engine.
TWO-STROKE CYCLE ENGINEAn internal
combustion engine requiring but two piston strokes
to complete the cycle of events that produce power.
UNIT FUEL INJECTORAn assembly which
receives fuel under supply pressure and is then
actuated by an engine mechanism to meter and
inject the charge of fuel to the combustion chamber
at high pressure and at the proper time.
UNIT PUMPAn injection pump containing no
actuating mechanism to operate the pumping
element or elements.
VALVEA mechanism that can be opened or closed to
control or stop the flow of a liquid, gas, or vapor
from one space to another.
VALVE-ACTUATING MECHANISMA group of
parts that work together to receive power from the
drive mechanism (camshaft) and transmit that
power to the engine valves.
VALVE GUIDEA hollow shaft pressed into the
cylinder head to keep the valve in proper alignment.
VALVE LASHClearance between the top of the
valve stem and the valve-lifting mechanism.
VALVE LIFTThe distance a valve moves from the
fully closed to the fully open position
VALVE OVERLAPThe period of crankshaft
rotation during which both the intake and exhaust
valves are open. It is measured in degrees.
VALVE REFACING MACHINEA
machine used to resurface the face and extend the
life of a valve.
VALVE RETAINERA device designed to lock the
valve-spring retainer to the valve stem.
VALVE ROTATORA mechanical device locked to
the end of the valve stem (used in place of a valve
spring retainer) that forces the valve to rotate about
5° with each rocker arm action.
VALVE SEATThe surface, normally curved, against
which the valve disk's operating face comes to rest
to provide a seal against leakage of liquid, gas, or
VALVE SEAT INSERTA metal ring inserted into
the valve seat, made of special metal that can
withstand engine operating temperatures.
VALVE SPRINGThe compression-type spring that
closes the valve when the valve-operating cam
assumes a closed-valve position.
VAPORIZATION A change of state from liquid to
vapor gas, by evaporation or boiling; a general term
including both evaporation and boiling.
VAPOR LOCKA condition in the fuel system in
which gasoline vaporizes in the fuel line or fuel
pump; bubbles of gasoline vapor restrict or prevent
fuel delivery to the carburetor.
VARIABLE SPEED FANAn engine fan that will
not exceed a predetermined speed or will rotate
only as fast as required to prevent engine
VENTURIIn the carburetor, a narrowed passageway
or restriction that increases the velocity of air mov-
ing through it, produces the vacuum responsible for
the discharge of fuel from the fuel nozzle.
VIBRATION An unceasing back and forth
movement over the same path; often with reference
to the rapid succession of motions of parts of an
VIBRATION DAMPERA weighted device that is
attached to the engine crankshaft at the end opposite
its power output. Its purpose is to absorb engine
VISCOSITYThe resistance to flow exhibited by a
liquid. A thick oil has a greater viscosity than a thin
VOLATILITYA measure of the ease with which a
liquid vaporizes. Volatility has a direct relationship
to the flammability of a fuel.
VOLUMEThe amount of air in the combustion
space of an engine cylinder.
VOLUMETRIC EFFICIENCYThe ratio between
the amount of air-fuel mixture that actually enters
an engine cylinder and the amount that could enter
under ideal conditions.
V-TYPE ENGINEAn engine with two banks of
cylinders set at an angle to each other in the shape of