Vacuum Advance

Vacuum Advance Chart:

1. Set the parking brake. Shift automatic transmission to PARK and manual transmission to the NEUTRAL position. The engine must be warmed to normal operation temperature.
2. Connect a timing light to the No. 1 spark plug wire. Connect a expanded scale tachometer.
3. Connect a hand-held vacuum pump to the distributor vacuum advance mechanism.
4. While observing the timing mark with the timing light, slowly apply vacuum on the vacuum advance mechanism.
5. The ignition timing should advance smoothly as applied vacuum increases. If no change in timing is seen check for ruptured diaphragm and replace as necessary.