Ignition timing control change-over system

摘要

An ignition timing control change-over system for an automotive internal combustion engine which has a spark retarding point in addition to a normal or spark advancing point. The system employs a change-over type relay switch for selectively and independently connecting either the spark advancing or the retarding point to the ignition coil in response to particular operating conditions of the engine. Under certain idling conditions of the engine, the spark retarding point of the distributor is connected to the ignition coil, and at the same time the throttle valve of the engine is opened by a throttle opener for temporarily increasing the engine speed to attain prompt warm-up of the engine and also of the exhaust gases. Unburned hydrocarbons and carbon monoxide contained in the exhaust may be reduced by a considerable degree as a result of this retarded control of the ignition timing under certain idling conditions of the engine.