Operation CHARM: Car repair manuals for everyone.

Vacuum Timing Controls

Vacuum Advance Hoses:





1. Upon cold start ensure that vacuum advance diaphragms A and B are supplied with manifold vacuum.

NOTE: If # 2 vacuum hose has no vacuum, check hose for cracks, blockage, and proper connection.
Remove check valve, apply vacuum to check valve one side at a time. One side should build vacuum and bleed off slowly while the other side should not build vacuum.
If # 25 hose has no vacuum, check the check valve and hoses # 24 and # 25 for cracks, blockage, and proper connection.
If no problems can be located in the check valve, hoses, or hose routing, replace the thermovalve and recheck vacuum hose # 25 for vacuum.

2. Allow engine to warm (cooling fans on).

NOTE: Check vacuum hose # 25 for vacuum. If vacuum exists replace thermovalve. Recheck vacuum hose # 25 for vacuum at normal operating temperature.

3. Turn ignition switch off.

4. Remove distributor cap and disconnect vacuum hoses from vacuum advance diaphragms.

5. Using a vacuum pump apply more than 20 in. Hg to one vacuum advance diaphragm.

6. Check that the stator rotates counterclockwise and stays. If the stator does not rotate or stay, replace vacuum advance diaphragm.

7. Repeat steps 5 and 6 for the other advance diaphragm port.

8. Reinstall distributor cap and connect vacuum advance hoses.

NOTE: Refer to ADJUSTMENT PROCEDURES section and adjust ignition timing