BIMETAL—Referring to the thermostatic bimetal element made up of two different metals with different heat expansion rates; temperature change produces a bending or distorting movement. BLOCK—See CYLINDER BLOCK BLOW-BY—Leakage  of  the  compressed  air-fuel mixture or burned gases from combustion, passing piston and rings, and into the crankcase. BLOWER—A  mechanical  device  for  compressing  and delivering   air   to   the   engine   at   higher   than atmospheric pressure. BOILING  POINT—The  temperature  at  which  a  liquid boils. BOOST PRESSURE—The pressure in the intake manifold while the turbocharger is operating. BORE—The diameter of a cylinder. Also used to describe the process of enlarging or accurately refinishing an engine cylinder. BRAKE  HORSEPOWER—The   power   actually delivered  by  the  engine  that  is  available  for  driving the  vehicle. AI-2 BTDC—Before top dead center. BUSHING—A replaceable lining for a hole in which a shaft, rod, or similar part moves. BUTTERFLY—The choke or throttle valve. BYPASS—A 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 requirements. CAM-GROUND—A process by which the piston is ground  slightly  egg-shaped  and,  when  heat becomes round. CAMSHAFT —The shaft in an engine that has a series of cam lobes for operating the valve mechanism. CAMSHAFT  PUMP—An injection pump containing a camshaft to operate the pumping element or elements. CARBON—A substance deposited on engine parts by the combustion of fuel.   Carbon forms on pistons, rings, valves, and so on, inhibiting their action. CARBON  DIOXIDE—A gas resulting from burning fuel. CARBON MONOXIDE—A  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 CONVERTER—A device used on the exhaust  system  of  gasoline  engines  to  reduce harmful emissions. CETANE—Ignition quality of diesel fuel. A high- cetane   fuel   ignites   more   easily   (at   lower temperature) than a low-cetane fuel. CFM—Cubic feet per minute. CHOKE—A 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. CID—Cubic inch displacement. CLOSED  CRANKCASE  VENTILATING SYSTEM—A  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 NOZZLE—A 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  CHAMBER—The 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  RATIO—The ratio between the volume in the cylinder with the piston at bottom dead center and with the piston at top dead center.