Ignition Timing: Adjustments

1. Remove the rubber cap from the inspection window of the cylinder block.
2. Start the engine and allow it to warm up (cooling fan comes on).
3. Connect a timing light to the engine.
4. Disconnect the vacuum hoses from the vacuum advance diaphragm and pinch the end of the hoses using fuel line clamps, 07614-0050100.







5. The timing should be 4° BTDC. If not, adjust by loosening the distributor adjusting bolts (and nut for fuel-injected engine), and turning the distributor housing counterclockwise to advance the timing or clockwise to retard the timing. Tighten the adjusting bolts (and nut for fuel-injected engine), recheck the timing.







6. Unplug the vacuum hose (# 5 for fuel-injected engine or # 2 for carbureted engine) and check for vacuum.

NOTE: Vacuum should be approximately 500 mmHg (20 in. Hg). If the vacuum is not as specified, check hoses and the intake manifold port.

7. Connect the vacuum hose (# 5 for fuel-injected engine or # 2 for carbureted engine) to advance diaphragm.
8. At idle, point the timing light toward the pointer and flywheel (for M/T), or the drive plate (for A/T).




Ignition Timing Specification:

Carbureted engine:

Manual Transmission: (at 750-850 rpm in neutral)
49 STATE and HIGH ALTITUDE: 22-26° BTDC (Red mark)
CALIFORNIA: 18-22° BTDC (Red mark)

Automatic Transmission (at 680-780 rpm in gear)
ALL MODELS: 13-17° BTDC (Red mark)

Fuel-Injected engine:

ALL MODELS: 13-17° BTDC (Red mark), (at 700-800 rpm in neutral).

NOTE: If the timing does not advance, inspect the advance diaphragm.







9. Unplug the vacuum hose (# 15 for fuel-injected engine or # 25 for carbureted engine) and check for vacuum at idle. There should be no vacuum. If there is vacuum;

Fuel-Injected Engine: Check the Ignition Control Solenoid Valve.

Carbureted Engine: Replace the Thermovalve B and retest.

10. On fuel-injected engine model, raise the engine speed to above 1,500 rpm and check for vacuum. There should be vacuum. If there is no vacuum, check the Ignition Control Solenoid Valve.

11. On carbureted engine model, when the coolant temperature is below 50°C (122° F), check for vacuum. There should be vacuum. If there is no vacuum, check the # 25 vacuum hose and the intake manifold port. If OK, replace the Thermovalve B and re-test.