How to Adjust Vacuum Advance: A Guide to Fine-Tuning Your Engine Performance
Adjusting the vacuum advance involves loosening the distributor clamp bolt and using a timing light to find the base timing. Then, the vacuum advance is disconnected and the engine is revved to check for timing advance. If the timing advance is too much or too little, the vacuum advance can be adjusted by turning the adjusting screw clockwise to decrease the advance or counter-clockwise to increase the advance. The process is repeated until the desired advance is achieved and then the distributor clamp bolt is tightened.