Vacuum Advance
- With distributor in test stand, check advance at vacuum settings shown in specifications. If tests indicate vacuum diaphragm unit is inoperative, out of calibration, or leaking, replace vacuum unit.
- Most types of vacuum diaphragm units are factory pre-set, and cannot be adjusted. However, on some dual diaphragm vacuum units, the vacuum advance may be increased or decreased by turning an Allen screw located in the end of diaphragm unit.