Ignition Changeover

Ignition timing is governed by centrifugal advance in distributor. Intake manifold vacuum is directed through a two-way valve to vacuum retard unit, which retards centrifugal advance for optimum performance and emission control. When cooling water reaches 100°C (212°F), due to engine overheating, temperature switch in thermostat housing actuates two-way valve, shutting off vacuum between intake manifold and retard unit on distributor.