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Main Jets

The nozzle in a carburetor that provides fuel during part- or full-throttle operation.

Main Journals

The journals that fit into the engine block to support the crankshaft.

Main Leaf

Usually the top leaf on multiple-leaf springs that provides the main vehicle support and contains the spring-mounting "eyes.".

Main-Body Structural Components

The assembly made up of the dash panel, underbody, roof, body panels, doors, and deck lid to form the passenger and luggage compartments.

Mainline Pressure

The pump-developed, hydraulic-regulated pressure that operates apply devices, such as bands, and is the source of all other pressures in an automatic transmission.

Mains

A term used for main bearings and main cap.

Maintenance Awareness Program (MAP)

A coalition of automobile repair shops, suppliers, car companies, and associations dedicated to building trust between the aftermarket and its customers.

Maintenance Manual

A manufacturer's or independent publication containing comprehensive maintenance information for a certain vehicle.

Maintenance Specifications

A listing of interval oil and lube grades, service points, and capacities for periodic routine preventative maintenance service.

Maintenance-Free Battery

A sealed battery having no practical provision for the addition of water to the cells, since periodic maintenance is unnecessary.

MAIR

Managed air injection reaction.

Major Diameter

1. The largest in diameter of a cylinder. 2. The largest in the diameter of a bolt, its threads.

Major Overhaul

An engine overhaul just short of a rebuild, where all worn or damaged parts are rebuilt or replaced.

Major Tune-up

A conventional, ignition-engine maintenance procedure that may include points, capacitor cap, rotor, plugs, plug wires, valve adjustment, and a carburetor overhaul.

Make

1. To close a switch. 2. A distinctive name given to a group of cars by a manufacturer, such as Riviera, by Buick.

Make And Break

1. The term used when a switch is closed or opened. 2. A pair of contact points, one stationary, and the other operated by a cam that makes the brake, such as in a conventional distributor. 3. To construct something then tear it down.

Make The Show

To qualify for a race.

Male

A term universally applied to any part which fits into another part, such as the shaft on which a pulley or gear hub fits.

Male And Female

Terms that apply to inner and outer members which fit together, such as a bolt and nut.

Malfunction

1.An improper or incorrect operation of a device or system. 2. The failure to work or perform.