Ignition Timing: Adjustments
Ignition Timing Inspection and Setting1. Start the engine and allow it to warm up (cooling fan comes on).
2. Disconnect the vacuum hoses from the vacuum advance diaphragm and, while the engine idles, check each hose for vacuum and plug the hoses.
^ The inside hose (# 12 for fuel-injected engine or # 2 for carbureted engine) should have vacuum.
^ The outside hose (# 15 for fuel-injected engine or # 25 for carbureted engine) should not have vacuum.
3. Connect an advance tester to the engine. While the engine idles, point a timing light toward the pointer at the crankshaft pulley.
4. Adjust ignition timing, if necessary, to the following specifications (color refers to timing mark indicator):
Fuel-Injected Engine
49 STATE:
HIGH ALTITUDE:
16°±2° BTDC (Red) at 750±50 rpm in neutral.
CALIFORNIA:
12°±2° BTDC (Red) at 750±50 rpm in neutral.
5. Loosen the distributor adjusting bolts, and turn the distributor housing counterclockwise to advance timing or clockwise to retard timing.
6. Tighten the adjusting bolts.
7. Recheck the timing and idle speed.
8. Disconnect the outside vacuum hose (# 15 or # 25) from the diaphragm and apply vacuum (more than 500 mmHg, 20 in.Hg), to the outside diaphragm with a vacuum pump.
The timing mark (Red) should advance an additional 4°.
9. Disconnect the vacuum hoses from the vacuum advance diaphragm and pinch the end of the hoses using fuel line clamps. The timing should be 4° BTDC.
10. If advance is not as specified, check the advance diaphragm and the distributor advance mechanism.