Spark Advance Control System (6 Cyl. Models)

At a speed of over 2500±100 RPM, speed sensitive relay opens circuit to two way valve. This allows valve to pass vacuum to advance side of distributor, thus advancing ignition timing. As engine speed drops below 2200 ± 100 RPM, relay closes, which causes valve to vent vacuum to the atmosphere. This eliminates vacuum advance. At increasing speeds, up to 2500 RPM, no vacuum advance is supplied.