How Does Vacuum Advance Work? Understanding the Mechanism and Benefits of Your Car’s Ignition System
The vacuum advance is a mechanism in a distributor that adjusts the timing advance of the ignition system in response to engine load. It works by using engine vacuum to move a diaphragm in the distributor, which in turn rotates the distributor shaft and adjusts the ignition timing. The vacuum advance helps to improve engine performance and fuel economy by allowing the ignition timing to be advanced under light-load conditions, such as cruising, when the engine is operating most efficiently.