Ignition Change Over

A two-way valve is incorporated in vacuum line between intake manifold and distributor vacuum retard unit. When two-way valve is not activated, vacuum is applied to diaphragm of vacuum unit which retards ignition timing. If coolant temperature is above 212°F, temperature switch is closed and this activates two-way valve, eliminating vacuum to distributor retard unit. Also, when air conditioning is switched on, two-way valve is also activated. This will cause ignition timing to be advanced by about 12°.