Glossary “dual quads” Definition:
Two four-barrel carburetors.

Glossary “dual reduction axle” Definition:
Drive axle construction with two sets of drive pinions, either of which can be used. Capable of producing two reduction speeds. Also called a two speed axle.

Glossary “dual trace” Definition:
Feature that allows the oscilloscope to display two separate waveforms at the same time.

Glossary “dual plug (DP)” Definition:
Ignition system which uses two spark plugs per cylinder to achieve better combustion.

Glossary “dual plug inhibit (DPI)” Definition:
Feature of a dual plug ignition system which allows the ignition system to operate either one plug or both plugs per cylinder.

Glossary “dual point system” Definition:
1). Ignition system with two sets of points in the distributor. 2). A system that controls spark timing by electro-mechanical selection of separate advance and retard points.

Glossary “dual plane crankshaft” Definition:
Crankshaft with two throws in two planes at right angles.

Glossary “dual plane manifold” Definition:
Intake manifold with two air cavities to provide air/fuel mixture to the cylinders.

Glossary “dual idler gear drive” Definition:
Timing gear system having two idler gears for the crankshaft to drive the camshaft.

Glossary “dual ignition system” Definition:
Ignition system having two coils and two distributors, with two spark plugs for each cylinder.

Glossary “dual mass flywheel” Definition:
Flywheel that consists of two parts separated by springs used to absorb vibrations in the driveline.

Glossary “dual master cylinder” Definition:
A master cylinder, associated with a dual-brake system, having two sections for displacing fluid under pressure; generally one section for front brakes and one section for rear brakes or, in some applications, one for left brakes and the other for right brakes.

Glossary “dual overhead camshaft” Definition:
Two cams in a single-cylinder head.

Glossary “dual diaphragm advance” Definition:
Vacuum advance mechanism with two diaphragms; one for normal ignition timing and the other to retard the spark during idling and part-throttle operation.

Glossary “dual diaphragm distributor” Definition:
Distributor incorporating a dual-diaphragm advance.

Glossary “dual exhaust” Definition:
Exhaust system used on V-type engines with a separate muffler, exhaust, and tail pipe for each cylinder bank.

Glossary “dual fuel engine” Definition:
1). Engine designed to run on two separate fuels, such as gasoline or propane. 2). Engine designed to run on two fuels simultaneously, such as gasoline, alcohol, or a combination of the two.

Glossary “dual hall sensor” Definition:
Device which contains a Hall Effect device to determine CID and another Hall Effect device to determine CKP and speed.

Glossary “dual brake system” Definition:
Brake system that uses two hydraulic circuits; should one fail, the other remains operational.

Glossary “dual camshaft” Definition:
Engine that has two camshafts for opening and closing additional valves.