Locate the vacuum advance canister on the distributor. It is usually a small, round, metal canister with a vacuum hose connected to it.
Disconnect the vacuum hose from the canister.
Using a screwdriver, turn the adjustment screw on the canister clockwise to increase vacuum advance or counterclockwise to decrease vacuum advance.
Reconnect the vacuum hose to the canister.
Start the engine and let it run for a few minutes.
Take note of the engine idle speed.
Turn the adjustment screw on the canister again until the engine idle speed drops about 50 RPM.
This will set the vacuum advance to the optimal setting for your engine.
