IGNITION TIMING - DISTRIBUTOR - MECHANICAL & VACUUM ADVANCE

Ignition timing, in a spark ignition internal combustion engine, is the process of setting the angle relative to piston position and crankshaft angular velocity that a spark will occur in the combustion chamber near the end of the compression stroke.

The need for advancing the timing of the spark is because fuel does not completely burn the instant the spark fires, the combustion gases take a period of time to expand, and the angular or rotational speed of the engine can lengthen or shorten the time frame in which the burning and expansion should occur.

Distributor is a device in a gasoline type engine wherein the electricity is transferred from the ignition coil to the spark plug thru high tension wires. Ignition timing can be advanced or retarded by turning the distributor. A use of timing light is highly recommended in adjusting ignition timing to ensure accurate reading and to avoid over-retarded or over-advanced timing. The distributor have essential parts that partially advancing the ignition timing depending on several factors like load; speed; driving habit; etc. These parts are called mechanical advance and vacuum advance. Properly working distributor advance will ensure that the ignition timing will be advance depending on the condition and driveability of the engine. Failure of the distributor advance will result to poor fuel mileage; loss of power; spark plug fouling (due to carbon deposit) and can result to engine failure.

Distributor will also require proper maintenance  just like carburetors to ensure that it will be dirt free and the moving parts will be lubricated.

The videos below will show what maintenance practices can be done to the distributor.

HOW TO: SET IGNITION TIMING W/ A TIMING LIGHT

HOW TO: UNINSTALL AND REINSTALL DISTRIBUTOR THE RIGHT WAY

HOW TO: DIAGNOSE DISTRIBUTOR ADVANCE - MECHANICAL AND VACUUM