Ignition System: Description and Operation

PURPOSE
The ignition system provides spark control to the engine during all modes of operation.

CONSTRUCTION
The ignition system consists of three sub systems:

^ Primary ignition - The primary ignition system includes the coil primary circuit, the power relay, the ignition module and the ignition switch.

^ Secondary ignition - The secondary ignition include the spark plugs, spark plug wires, distributor cap, distributor rotor, coil wire and the coil secondary circuit.

^ Timing advance - Advance is controlled one of two ways, depending on application:
- Electronic Control Assembly (ECA)
- Governor weights and advance/retard vacuum diaphragms.

LOCATION
All engines use a distributor mounted on the engine and driven directly off the camshaft.

OPERATION
When the ignition switch is turned ON, the power relay closes and charges the primary coil windings. When the engine is running, the ignition module grounds the negative side of the primary coil circuit which induces spark. Spark is routed from ignition coil to distributor where the rotor and distributor cap route spark to each spark plug.