Dictionary of Automotive Terms: C

CAFE: Corporate Average Fuel Economy.

CALIBRATE: As applied to test instruments—adjusting dial needle to correct zero or load setting.

CALIPER (Brake): Disc brake component which forms cylinder and houses piston and brake pads (linings). It produces clamping action on rotating disc to stop car.

CALIPERS (Inside and Outside): Adjustable measuring tool placed around or within an object and adjusted until it just contacts. It is then withdrawn and distance measured between contacting points.

CALORIE (Gram): A unit of heat. Amount of heat required to raise the temperature of one gram of water 1 deg. centigrade.

CALORIFIC VALUE: Measurement of the heating value of fuel.

CALORIMETER: Measuring instrument used to determine amount of heat produced when a substance is burned; also friction and chemical change heat production.

CAM: Offset portion of shaft that will, when shaft turns, impart motion to another part such as valve lifters.

CAM ANGLE or DWELL (Ignition): Number of degrees breaker cam rotates from time breaker points close until they open again.

CAM GROUND: Piston ground slightly egg- shaped. When heated, it becomes round.

CAMBER: Tipping top wheel centerline out ward produces positive camber. Tipping wheel centerline inward at top produces negative camber. When camber is positive, tops of tires are further apart than bottom.

CAMSHAFT: Shaft with cam lobes (bumps) used to operate valves.

CAMSHAFT GEAR: Gear that's used to drive camshaft.

CANDLE POWER: Measurement of light producing ability of light bulb.

CAP: Cleaner Air Package System of reducing amount of unburned hydrocarbons in automobile exhaust.

CAPACITANCE: Property of condenser that permits it to receive and retain an electrical charge.

CAPACITOR: See Condenser.

CARB: California Air Resources Board.

CARBON: Used to describe hard, or soft, black deposits found in combustion chamber, on plugs, under rings, on and under valve heads, etc.

CARBONIZE: Building up of carbon on objects such as spark plugs, pistons, heads, etc.

CARBON MONOXIDE: Deadly, colorless, odorless, and tasteless gas found in engine exhaust. Formed by incomplete burning of hydrocarbons.

CARBON PILE: Refers to amperage or voltage regulator utilizing a stack of carbon discs in its construction.

CARBURETOR: Device used to mix gasoline and air in correct proportions.

CARBURETOR ADAPTER: Adapter used to fit or place one type of carburetor on an intake manifold that may not be originally designed for it. Also used to adapt four-barrel carbs to two-barrel manifolds.

CARBURETOR CIRCUITS: Series of passageways and units designed to perform a specific function — idle circuit, full power circuit, etc.

CARBURETOR ICING: Formation of ice on throttle plate or valve. As fuel nozzles feed fuel into air horn, it turns to a vapor. This robs heat from air and when weather conditions are just right (fairly cold and quite humid), ice may form.

CARBURIZING FLAME: Welding torch flame in which there is an excess of acetylene.

CARDAN JOINT: Type of universal joint.

CARRIER BEARINGS: Bearings upon which differential case is mounted.

CASE-HARDENED: Piece of steel that has had outer surface hardened while inner portion remains relatively soft.

CASTER: Tipping top of kingpin either for ward or toward the rear of car. When tipped forward, it's termed negative caster. When tipped toward rear, it's termed positive caster.

CASTING: Pouring metal into a mold to form an object.

CASTLE or CASTELLATED NUT: Nut having series of slots cut into one end, into which cotter pin may be passed to secure nut.

CATALYTIC CONVERTER: Device used in exhaust system to reduce harmful emissions. Catalyst in converter may be coated with palladium, platinum, and rhodium. Catalyst may be of oxidizing and/or reducing design.

CATHODE: In electric circuit —the negative pole.

CCS: Controlled Combustion System of reducing unburned hydrocarbon emission from engine exhaust.

CEC: Combination Emission Control.

CELL ( Battery): Individual (separate) compartments in battery which contain positive and negative plates suspended in electrolyte. Six-volt battery has three cells, twelve-volt battery six cells.

CELL CONNECTOR: Lead strap or connection between battery cell groups.

CENTERLINE: Imaginary line drawn lengthwise through center of an object.

CENTER LINK: Also called relay rod or connecting link, it transfers motion from pit- man arm to tie rods.

CENTER OF GRAVITY: Point in object, if through which an imaginary pivot line were drawn, would leave object in balance. In car, the closer the weight to the ground, the lower the center of gravity.

CENTER STEERING LINKAGE: Steering system utilizing two tie rods connected to steering arms and to central idler arm. Idler arm is operated by drag link that connects idler arm to pitman arm.

CENTIGRADE: Thermometer on which boiling point of water is 100 deg. and freezing point is 0 deg.

CENTRIFUGAL ADVANCE (Distributor): Unit designed to advance and retard ignition timing through action of centrifugal force.

CENTRIFUGAL CLUTCH: Clutch that utilizes centrifugal force to expand a friction device on driving shaft until it's locked to a drum on driven shaft.

CENTRIFUGAL FORCE: Force which tends to keep moving objects traveling in straight line. When moving car is forced to make a turn, centrifugal force attempts to keep it moving in straight line. If car is turning at too high a speed, centrifugal force will be greater than frictional force between tires and road and the car will slide off the road.

CERAMIC FILTER: Filtering device utilizing porous ceramic as filtering agent.

CETANE NUMBER: Measurement of diesel fuel performance characteristics.

CFM: Cubic feet per minute. A measure of air flow.

CHAMFER: To bevel (or a bevel on) edge of an object.

CHANGE OF STATE: Condition in which substance changes from a solid to a liquid, a liquid to a gas, a liquid to a solid, or a gas to a liquid.

CHARCOAL CANISTER: Emission control device containing activated charcoal granules. Used to store gasoline vapors from tank and carburetor. When engine is started, stored vapors are drawn into cylinders and burned.

CHARGE (Air Conditioning): A given or specified (by weight) amount of refrigerant.

CHARGE ( Battery): Passing electric current through battery to restore it to active (charged) state.

CHARGE RATE: Electrical rate of flow, in amperes, passing through the battery during charging.

CHARGING (Air Conditioning): Inserting the specified charge (amount) of refrigerant into the air conditioning system.

CHASE: To repair damaged threads.

CHASSIS: Generally, chassis refers to frame, engine, front and rear axles, springs, steering system and gas tank. In short, every thing but body and fenders.

CHASSIS DYNAMOMETER: See Dynamometer.

CHECK VALVE: Valve that opens to permit passage of fluid or air in one direction and closes to prevent passage in opposite direction.

CHILLED IRON: Cast iron possessing hardened outer skin.

CHOKE: Butterfly valve located in carburetor used to enrichen mixture for starting engine when cold.

CHOKE STOVE: Heating compartment in or on exhaust manifold from which hot air is drawn to automatic choke device.

CID: Cubic Inch Displacement.

CIRCUIT (Electrical): Source of electricity (battery), resistance unit (headlight, etc.) and wires that form path for flow of electricity from source through unit and back to source.

CIRCUIT BREAKER (Lighting System): Protective device that will make and break flow of current when current draw becomes excessive. Unlike fuse, it does not blow out but vibrates on and off thus giving driver some light to stop by.

CLEARANCE: Given amount of space between two parts — between piston and cylinder, bearing and journal, etc.

CLOCKWISE: Rotation to right as that of clock hands.

CLOSED COOLING SYSTEM: Type of sys tem which uses an overflow tank.

CLOSED LOOP FUEL SYSTEM: A fuel system in which air-fuel ratio is constantly adjusted in relationship to hydrocarbon con tent of exhaust. An oxygen sensor in exhaust, working through an electronic control unit, alters either carburetor jet size or fuel injection system pulse width.

CLUSTER or COUNTER GEAR: Cluster of gears that are all cut on one long gear blank. Cluster gears ride in bottom of transmission. Cluster provides a connection between transmission input shaft and output shaft.

CLUTCH: Device used to connect or disconnect flow of power from one unit to another.

CLUTCH DIAPHRAGM SPRING: Round dish-shaped piece of flat spring steel. Used to force pressure plate against clutch disc in some clutches.

CLUTCH DISC: Part of clutch assembly splined to transmission clutch or input shaft. Faced with friction material. When clutch is engaged, disc is squeezed between flywheel and clutch pressure plate.

CLUTCH EXPLOSION: Clutches have literally flown apart (exploded) when subjected to high rpm. Scatter shield is used on competition cars to protect driver and spectators from flying parts in event clutch explodes.

CLUTCH HOUSING or BELL HOUSING: Cast iron or aluminum housing that surrounds flywheel and clutch mechanism.

CLUTCH LINKAGE: Mechanism which transfers movement from clutch pedal to throw-out fork.

CLUTCH PEDAL FREE TRAVEL: Specified distance clutch pedal may be depressed before throw-out bearing actually contacts clutch release fingers.

CLUTCH PILOT BEARING: Small bronze bushing, or in some cases ball bearing, placed in end of crankshaft or in center of flywheel depending on car, used to support outboard end of transmission input shaft.

CLUTCH PRESSURE PLATE: Part of a clutch assembly that through spring pres sure, squeezes clutch disc against flywheel thereby transmitting driving force through the assembly. To disengage clutch, pressure plate is drawn away from flywheel via linkage.

CLUTCH SEMI-CENTRIFUGAL RELEASE FINGERS: Clutch release fingers that have a weight attached to them so that at high rpm release fingers place additional pressure on clutch pressure plate.

CLUTCH THROW-OUT FORK: Device or fork that straddles throw-out bearing and used to force throw-out bearing against clutch release fingers.

CO: Symbol for carbon monoxide.

COIL (Ignition): Unit used to step up battery voltage to point necessary to fire spark plugs.

COIL CORE: Multilayered mass of iron around which coil windings are wrapped. Some designs place core outside of windings.

COIL SPRING: Section of spring steel rod wound in spiral pattern or shape. Widely used in both front and rear suspension systems.

COLD: Little or no perceptible heat.

COLD CRANKING RATING ( Battery): Measurement of cranking amperes that a battery can deliver over a period of 30 seconds at 0°F (- 17.8°C) and still maintain a minimum cell voltage of 1.2 volts.

COLD START INJECTOR: Fuel injector which sprays additional fuel for cold engine starting.

COLLAPSED (Piston): Piston whose skirt diameter has been reduced due to heat and forces imposed upon it during service in engine.

COMBUSTION: Process involved during burning.

COMBUSTION CHAMBER: Area above piston with piston on TDC. Head of piston, cylinder, and head form the chamber.

COMBUSTION CHAMBER VOLUME: Volume of combustion chamber (space above piston with piston on TDC) measured in cc (cubic centimeters).

COMMUTATOR: Series of copper bars connected to armature windings. Bars are insulated from each other and from armature. Brushes (as in generator or starter) rub against whirling commutator.

COMPENSATING PORT: Small hole in brake master cylinder to permit fluid to return to reservoir.

COMPENSATOR VALVE (Automatic Transmission): Valve designed to increase pressure on brake band during heavy acceleration.

COMPOUND: Two or more ingredients mixed together.

COMPRESSION: Applying pressure to a spring, or any springy substance, thus causing it to reduce its length in direction of compressing force. Applying pressure to gas, thus causing reduction in volume.

COMPRESSION CHECK: Testing compression in all cylinders at cranking speed. All plugs are removed, compression gauge placed in one plug hole, throttle cracked wide open and engine cranked until gauge no longer climbs. Compression check is a fine way in which to determine condition of valves, rings and cylinders.

COMPRESSION GAUGE: Gauge used to test compression in engine cylinders.

COMPRESSION RATIO: Relationship between cylinder volume (clearance volume) when piston is on TDC and cylinder volume when piston is on BDC.

COMPRESSION RINGS: Top piston rings, generally two, designed to seal between piston and cylinder to prevent escape of gas from combustion chamber.

COMPRESSION STROKE: Portion of piston’s movement devoted to compressing the fuel mixture trapped in engine’s cylinder.

COMPRESSOR (Air Conditioning): Device using a series of pistons to raise pressure of refrigerant in system. Also causes refrigerant to flow through system.

COMPRESSOR PROTECTION SWITCH: (Air Conditioning): A heat and/or pressure sensitive switch to protect compressor from damage caused by loss of oil and over heating.

COMPUTERIZED IGNITION: Ignition system using sensors which feed electrical in formation to computer. Computer then controls ignition system and sometimes other functions (carburetor, fuel injection, transmission) for maximum efficiency.

CONCENTRIC: Two or more circles so placed as to share common center.

CONDENSE: Turning vapor back into liquid.

CONDENSER (Ignition): Unit installed between breaker points and coil to prevent arcing at breaker points. Condenser has ability to absorb and retain surges of electricity.

CONDENSER (Refrigeration): Unit in air conditioning system that cools hot com pressed refrigerant and turns it from vapor into liquid.

CONDENSATION: Moisture, from air, deposited on a cool surface.

CONDUCTION: Transfer of heat from one object to another by having objects in physical contact.

CONDUCTOR: Material forming path for flow of current.

CONE CLUTCH: Clutch utilizing cone- shaped member that's forced into a cone- shaped depression in flywheel, or other driving unit, thus locking two together. Al though no longer used on cars, cone clutch finds some applications in small riding tractors, heavy power mowers, etc.

CONNECTING ROD: Connecting link between piston and crankshaft.

CONNECTING ROD BEARINGS: Inserts which fit into connecting rod and ride on crankshaft journals.

CONNECTING ROD CAP: Lower removable part of rod which holds lower bearing insert.

CONSTANT DRIVE OVERDRIVE: An overdrive unit that, when engaged, is constantly connected to drive wheels and will not permit freewheeling (coasting).

CONSTANT MESH GEARS: Gears that are always in mesh with each other.

CONSTANT VELOCITY UNIVERSAL JOINT: Universal joint so designed as to effect smooth transfer of torque from driven shaft to driving shaft without any fluctuations in speed of driven shaft.

CONTACT POINTS also called BREAKER POINTS: Two removable points or areas that when pressed together, complete circuit. These points are usually made of tungsten, platinum or silver.

CONTINUOUS FUEL INJECTION: A fuel injection system in which injectors are always open and as such, feed fuel constantly. Amount of fuel delivered can be determined by an airflow sensor.

CONTRACTION (Thermal): Reduction in size of object when cooled.

CONTROL RACK: Toothed rod inside mechanical injection pump which rotates pump plunger to control quantity of injected fuel.

CONVECTION: Transfer of heat from one object to another when hotter object heats surrounding air and air in turn heats other object.

COOLANT: Liquid in cooling system.

COOLING SYSTEM: System, air or water, designed to remove excess heat from engine. CORE: When referring to casting—sand unit placed inside mold so that when metal is poured, core will leave a hollow shape.

CORONA (Electrical): Luminous discharge of electricity visible near surface of an electrical conductor under high voltage.

CORRODE: Removal of surface material from object by chemical action.

COUNTERBALANCE: Weight attached to some moving part so part will be in balance. COUNTERBORE: Enlarging hole to certain depth.

COUNTERCLOCKWISE: Rotation to the left as opposed to that of clock hands.

COUNTERSHAFT: Intermediate shaft that receives motion from one shaft and transfers it to another. It may be fixed (gears turn on it) or it may be free to revolve.

COUNTERSINK: To make a counterbore so that head of a screw may set flush, or below the surface.

COUPLING: Connecting device used between two objects so motion of one will be imparted to other.

COUPLING POINT: This refers to point at which both pump and turbine in torque converter are traveling at same speed. The drive is almost direct at this point.

COWL: Part of car body between engine firewall and front of dash panel.

CRANKCASE: Part of engine that surrounds crankshaft. Not to be confused with the pan which is a thin steel cover that's bolted to crankcase.

CRANKCASE DILUTION: Accumulation of unburned gasoline in crankcase. Excessively rich fuel mixture or poor combustion will allow some of gasoline to pass down between pistons and cylinder walls.

CRANKCASE VENTILATION: Process of drawing clean air through interior of engine to remove blow-by gases and other fumes.

CRANKING MOTOR: Starter. Device to revolve engine crankshaft to start engine. Works through a gear engaging another gear on flywheel.

CRANKSHAFT: Shaft running length of engine. Portions of shaft are offset to form throws to which connecting rods are attached. Crankshaft is supported by main bearings.

CRANKSHAFT GEAR: Gear mounted on front of crankshaft. Used to drive camshaft gear.

CRANKSHAFT THROW: Offset part of crankshaft where connecting rods fasten.

CROSS AND ROLLER: Type of universal joint using a center cross (spider) mounted in needle bearings.

CROSS SHAFT (Steering): Shaft in steering gearbox that engages steering shaft worm. Cross shaft is splined to pitman arm.

CRUDE OIL: Petroleum in its raw or unrefined state. It forms the basis of gasoline, engine oil, diesel oil, kerosene, etc.

CUBES: Cubic inches, or cubic inch displacement of an engine.

CU. IN. (C.I.): Cubic inch.

CUNO FILTER: Filter made up of a series of fine discs or plates pressed together in a manner that leaves very minute space between discs. Liquid is forced through these openings to produce straining action.

CURRENT: Movement of free electrons through conductor.

CUTOUT (Regulator): Device to connect or disconnect generator from battery circuit. When generator is charging, cutout makes circuit. When generator stops, cutout breaks circuit. Also referred to as cutout relay, and circuit breaker.

CYCLE: Recurring period during which series of events take place in definite order.

CYLINDER: Hole, or holes, in cylinder block that contain pistons.

CYLINDER BLOCK: See Block.

CYLINDER BORE: See Bore.

CYLINDER HEAD: Metal section bolted on top of block. Used to cover tops of cylinders. In many cases cylinder head contains the valves. Also forms part of combustion chamber.

CYLINDER HONE: Tool that uses an abrasive to smooth out and bring to exact measurements such as engine cylinders, wheel cylinders, bushings, etc.

CYLINDER LINER: See Cylinder Sleeve.

CYLINDER SLEEVE: Replaceable cylinder. It is made of a pipe-like section that's either pressed or pushed into the block.

CYLINDER STROKE: See Stroke.