IDLE-MIXTURE SCREWThe adjustment screw
(on some carburetors) that can be turned in or out to
lean or enrich the idle mixture.
IDLE SPEEDThe speed, or rpm, at which the engine
runs when the accelerator pedal is fully released and
there is no load on the engine.
generated by compression in an internal
combustion engine ignites the fuel (as in a diesel
IGNITION-SPARKWhen the mixture of air and
fuel in an internal combustion engine is ignited by
an electric spark (as in a gasoline engine).
IGNITION TIMINGRefers to the timing of the
spark at the spark plug as related to the piston in the
INJECTION/IGNITIONWhen the piston nears the
top of its stroke, fuel admitted under pressure is
sprayed into the cylinder. The fuel ignites due to the
heat in the cylinder.
INJECTION PUMPThe device which meters the
fuel and delivers it under pressure to the nozzle and
INJECTION PUMP ASSEMBLYA complete
assembly consisting of the fuel pump proper,
together with additional units such as governor, fuel
supply pump, and additional optional devices,
when these are assembled with the injection pump
to form a unit.
INJECTION TIMINGThe matching of the pump
timing mark, or the injector timing mechanism, to
some index mark on an engine component, such
that injection will occur at the proper time with
reference to the engine cycle.
INJECTOR The mechanism, including nozzle, that
injects fuel into the engine combustion chamber on
IN-LINE ENGINEAn engine in which the cylinders
are arranged in one straight line.
IN-LINE PUMPAn injection pump with two or
more pumping elements arranged in line, each
pumping element serving one engine cylinder only.
INTAKE MANIFOLDThat component of the
engine that provides a series of passages to allow
the air-fuel mixture to flow to the engine cylinders.
INTAKE STROKEThe piston stroke from top dead
center to bottom dead center during which the
intake valve is open and the cylinder receives a
charge of air-fuel mixture.
INTAKE VALVEThe valve in the engine that is
opened during the intake stroke to permit the
entrance of the air-fuel mixture into the cylinder.
INTERNAL COMBUSTION ENGINEAn engine
in which the fuel is burned inside the engine, as
opposed to an external combustion engine where
the fuel is burned outside the engine, such as a
JOURNALServes as the point of support and the
center of rotation for the shaft. That part of the shaft
that is prepared to accept a bearing (connecting rod,
KNOCKA heavy metallic engine sound that varies
with engine speed; usually caused by a loose or
worn bearing; name also used for detonation,
pinging, and spark knock. See DETONATION.
L-HEADA type of engine with the valves located in
the cylinder block.
LAPTo work two surfaces together with abrasive
until a very close fit is produced; to polish.
LASHThe clearance or play between adjacent
movable mechanical parts. See VALVE LASH.
LEAN MIXTUREA air-fuel mixture that has a high
proportion of air and a low proportion of fuel.
LUBRICATION SYSTEMThe system in the
engine that supplies the engine with lubricating oil
to prevent contact between any two moving metal
MANIFOLDA device with several inlet or outlet
passageways through which a gas or liquid is
gathered or distributed. See INTAKE MANIFOLD
and EXHAUST MANIFOLD.
MECHANICAL EFFICIENCYIn an engine, the
ratio between brake horsepower and indicated
MECHANICAL GOVERNORA speed sensitive
device of the centrifugal type, which controls the
injection pump delivery sole by mechanical means.
MICROMETERA measuring device that measures
accurately such dimensions as shaft or bore
diameter or thickness of an object.