Rodding Roundtable
Rodding Terms - Motor Related

  • 3/4 Race Cam - A camshaft that was not "Full Race", but still offers more performance than a stock cam.
  • Ammeter - An instrument used to measure the rate of electrical current flow in amperes.
  • Alternator(ALT) - A device which produces alternating current (AC) by converting the engine's turning (mechanical) energy into alternating electrical current at all engine speeds. The AC must be rectified (converted from AC to DC) before reaching the vehicle's electrical system. The alternator is driven by a belt at the front of the engine. Alternators replaced the direct-current (DC) generators used up to the 1960's because they were less efficient especially at idle. The electrically demanding options like air conditioning forced the use of alternators over generators.
  • Ardun Heads - Hemispherical aluminum over-head valve cylinder heads, designed by Zora Arkus-Duntov from whom they derive their name.
  • Automatic Transmission - A transmission where the gears are shifted automatically by the vehicle and controlled by a torque converter.
  • Ballast Ignition System - An ignition system which uses a ballast resistor connected in series with the coil primary winding and which is bypassed when the starter is engaged so that the spark is more efficient under cold weather starting.
  • Bored and Stroked - Cylinders have been enlarged and crank has been modified to increase engine displacement.
  • Bell Housing - Housing which encloses the clutch disc or torque converter.
  • Blueprint - Process for assuring that every measurement of an engine is exactly meets the factory specification.
  • Bumpstick - See Camshaft.
  • Camshaft - The shaft in the engine which is driven by gears, belts or chain from the crankshaft. The camshaft has a series of cams that opens and closes intake and exhaust valves as it turns.
  • Capacitive Discharge(CD) - A type of ignition system. It can be either all-electronic or breaker point controlled. The primary power is drawn from the engine's battery and put into the CD power supply, where it is changed from 12 volts direct current to about 300 volts of pulsating direct current that is stored in a capacitor (condenser). The release of this energy through the coil is governed by a silicon-controlled rectifier (SCR). When the SCR switch is closed, the voltage stored in the capacitor is supplied to the coil, which acts as a voltage step-up transformer boosting firing voltage to around 30,000 volts to fire the plugs.
  • Compression Ratio - The degree to which air or an air-fuel mixture is compressed. An 8:1 compression ratio means that the mixture is compressed to 1/8th its original size.
  • Condenser - A device for storing electrical energy. In A/C application, an air conditioning component used to remove heat from the inside of a vehicle.
  • Clutch Disc - A disc covered with a friction material that is used to transfer engine power to the transmission.
  • Cut Outs - Devices installed to allow the exhast to exit the system before the mufflers and tailpipes.
  • Distributor -
  • Dual Quad - is slang for two, four-barrel carburetors found only on high performance automobiles.
  • Engine Turned - A process that involves coating a metallic surface with an oil and sand mixture and then using a drill press fitted with a special mandrel to create striking swirl patterns. Also called Damascening.
  • Fuel Injection - Fuel injection is an electronic system that increases performance and fuel economy because it monitors engine conditions and provides the correct air/fuel mixture based on the engine's demand. Unlike a carburetor, which mixes fuel and air together before loading it into the cylinder intake port, fuel injection injects the fuel directly into the cylinder head enabling more precise control over the quantity used. Eliminates need for a carburetor and the complex, imprecise tuning that goes with it.
  • Full House - An engine that has had all the modifications including boring, stroking, porting, and polishing. Not necessarily a race engine as many full house motors are driven on the street.
  • Generator - A device that converts mechanical energy into electrical energy. It can produce either AC or DC electricity. Seldom used in automotive applications, it has been replaced by the alternator.
  • Hemi - Engine using hemispherical-shaped (half of a globe or sphere) combustion chambers. The valves are cocked at 45 degrees from the piston top. Mopars, despite their fame, are not the only cars with hemi heads.
  • High-rise Manifold - An intake manifold designed to mount the carburetor or carburetors, considerably higher above the engine than is done in the standard manifold. This is done to improve the angle at which the fuel is delivered.
  • High Energy Ignition System(HEI) - An ignition system which provides more ignition power (higher voltage at higher amperage) than normal systems; a typical HEI includes an electronic control unit and magnetic pick-up in combination with mechanical ignition timing.
  • Intake Manifold - Tubing attached to the engine through which the air/fuel mixture reaches the cylinder.
  • Ignitor - See Distributor
  • Loud Pedal - The accelerator pedal.
  • Magneto - A magneto is a simplified ignition system that directly converts the motion of kicking or cranking into a high voltage spark. Since it works independently, it will still function with a faulty electrical system, a dead battery or no battery at all.
  • Normally Aspirated Engine - An engine where all the air to the cylinders is not forced in, as with turbo chargers or super chargers.
  • Overhead Valve Engine(OHV) - An engine with both intake and exhaust valves placed directly over the piston. In this design, the camshaft is located in the block, and the valves are actuated by pushrods and rocker arms.
  • Overhead Cam - The type of valve train arrangement in which the engine's camshaft is mounted above the cylinder head(s). When the camshaft is placed close to the valves, the valve train components can be stiffer and lighter, allowing the valves to open and close more rapidly and the engine to run at a higher RPM. In a single overhead cam (SOHC) layout, one camshaft actuates all of the valves in a cylinder head. In a dual overhead camshaft (DOHC) layout, one camshaft actuates the intake valves, and one camshaft operates the exhaust valves.
  • Overdrive - A transmission in which the highest gear ratio is less than a one-to-one ratio. This means the drive shaft turns faster than the engine crankshaft. The overdrive feature saves fuel and, because the engine runs slower, engine wear and noise are reduced.
  • Pop Ups - Domed top pistons to increase static compression.
  • Radiator - The device through which air passes to cool a single system in a car. Normally, it is used to cool engine coolant. Conversely it can cool engine oil. In the case of a turbocharged car, a radiator cools the air being forced into the engine and is called an intercooler.
  • Rich Mixture - The condition that exists when the ratio of fuel to air is very high. A rich mixture can contribute to inefficient burning of fuel, resulting in poor mileage, higher emissions and black smoke from the exhaust pipe.
  • Solenoids - Solenoids are electro-magnetic switches. When electricity is sent to the solenoid, a magnetic field forms. The magnetic field moves a metal piston that is connected to a mechanical linkage or in this case, a valve. When the metal piston moves, the application is made. The application may be the moving of a valve in the valve body to activate second gear.
  • Starter Solenoid - The electromagnetic switch that routes electric current to the starter when the starter switch is turned on or pushed on an automobile or motorcycle. Also called a starter relay.
  • Stroke - This refers to the distance a piston moves from the top of its motion against the cylinder head to the other extreme at the lower end of the cylinder. It is determined by multiplying that distance by the area of the piston. The displacement or size of the engine is usually expressed in cubic inches or cubic liters.
  • Supercharged Engine - An engine that is similar to a turbocharged engine which uses a series of belts or chains from the crankshaft to turn the turbines that forces the air/fuel mixture into the cylinder heads under pressure creating a bigger explosion which generates more power. A turbocharger use the exhaust gases to turn the turbines to create the same effect.
  • Torque Converter - Is a type of fluid coupling, which allows the engine to spin somewhat independently of the transmission.
  • Tunnel Ram - A hise rise intake that usually has runners of considerable length.
  • Variable Valve Timing - Engine valves can be adjusted to create higher fuel-to-air ratios. The higher the ratio, the bigger the explosion that drives the engine and thus more power.

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