Ignition System: Description and Operation

Fig.18 - Dual Breaker Point Distributor System:

The dual breaker points distributor, Fig. 18, uses two sets of breaker points which permit automatic selection of ignition timing. The retarded breaker points are used when the engine is accelerated or decelerated. The advanced breaker points are for normal engine operation.

The two sets of breaker points are positioned with a relative phase angle of 4° apart, and are connected in parallel in the primary side of the ignition circuit. A distributor relay is inserted in the retarded breaker point circuit and accelerator and transmission relays, throttle and ignition relays are connected in parallel with the distributor relay.

When the distributor relay is energized and any of the following conditions are met; transmission is in other than 3rd or 4th gear, carburetor throttle valve opening is less than 7° or greater than 35°, clutch pedal is depressed, or when ignition switch is turned on, the advance breaker points come into operation.

The retarded breaker points come into operation when any of the above conditions do not apply.

The throttle switch is controlled by the cam interlocked with the primary side of the throttle valve, and is activated when the throttle valve is opened beyond 35°.

The distributor relay is energized by the operation of the ignition switch, accelerator relay, transmission relay, throttle switch or clutch relay. Under any one of these conditions, the distributor circuit it switched from the retarded breaker point circuit to the advanced breaker point circuit.

When the distributor relay is de-energized, the distributor circuit is switched from the advanced breaker point circuit to the retarded breaker point circuit.