• A timing light
• An adjustable wrench
• A flathead screwdriver
• A feeler gauge
1. Park the vehicle on a level surface and turn off the engine.
2. Locate the ignition coil. It is mounted on the front of the engine, near the distributor cap.
3. Disconnect the vacuum hose from the ignition coil.
4. Start the engine and let it run for a few minutes until it reaches operating temperature.
5. Connect the timing light to the battery and the ignition coil.
6. Point the timing light at the timing marks on the engine crankshaft pulley.
7. Turn the adjustable wrench to loosen the distributor hold-down bolt.
8. Use the flathead screwdriver to turn the distributor body clockwise or counterclockwise until the timing mark aligns with the pointer.
9. Tighten the distributor hold-down bolt.
10. Recheck the timing to ensure that it is set correctly.
11. Reconnect the vacuum hose to the ignition coil.
12. Turn off the engine.
13. Turn the key back ON without starting the engine. This puts power to the ignition coil.
14. Check for spark between the coil and the distributor. There should be a spark every time the points open. This tells you that the ignition timing is close enough to start the engine.
To fine tune the timing with a feeler gauge:
15. Turn off the engine.
16. Disconnect the wire you connected back in step 13 above.
17. Remove the distributor cap and rotor from the distributor.
18. Locate the points. They are located under the rotor.
19. Insert the feeler gauge between the points.
20. Turn the distributor body until the points just begin to open.
21. Install the distributor cap and rotor.
22. Install the wire you removed in step 15 above.
23. Start the engine and recheck the timing with the timing light.
This should set the timing on the 1989 Ford Aerostar. Refer to a repair manual for your vehicle to verify the gap specifications for the points.
