Distributor Vacuum Control: Testing and Inspection

1. Connect tee fittings to ports 1 and 4, then connect a suitable vacuum gauge to each tee fitting.
2. Start engine and check vacuum gauges. Vacuum should be equal.
3. Quickly depress throttle. Vacuum at port 1 should decrease instantly and vacuum at port 4 should be maintained momentarily.
4. Stop engine and remove gauges and tee fittings. If defective, replace valve.