System Testing

Fig. 76 HAC Valve Air Filter:

Fig. 77 Testing HAC Valve At High Altitude:

FEDERAL AND CANADIAN MODELS ONLY

1. Remove the cap from the bottom of the EBCV and inspect the HAC valve air filter. Fig. 76
2. Clean the filter and reinstall.
3. With the HAC valve at high altitude, (Above 3,930 ft.), and the engine idling, blow into any of the air ports on top of the valve.
4. Check that the valve exhausts air through the air filter. Fig. 77
5. If you are at a low altitude, (Below 2,570 ft.), when performing this test, the valve filter should be closed to air passage.
6. Reconnect all hoses to the EBCV and maintain idle speed.
7. Disconnect the distributor sub-diaphragm vacuum hoses and plug the hose ends.
8. Using a strobe timing light, check the ignition timing.

Ignition Timing: 5° BTDC at Max. 950 rpm

9. Reconnect the vacuum hoses to the sub-diaphragm ports and recheck the timing.

Ignition Timing: Approx. 13° BTDC at Max. 950 rpm

Fig. 78 Testing Ignition Timing Delay:

10. Disconnect the vacuum hose from the black side of the check valve, (Located near the distributor), and plug the hose end. Fig. 78
11. Check that the ignition timing remains fixed for at least one minute.
12. If any problems are found, test each HAC component in the system.
13. Reconnect all vacuum hoses and remove timing light from the engine.