Ignition Timing: Adjustments

Ignition Timing Procedure

Adjustable Timing Lamp:

1. Connect a suitable Power Timing Light to number one cylinder.

Note: Do not puncture cables, boots or nipples with test probes. Always use power adapters. Puncturing the spark plug cables with a probe will damage the cables. The probe can separate the conductor and cause high resistance. In addition breaking the rubber insulation may permit secondary current to arc to ground.

Coil Terminals:

2. Connect the red leak of the test tachometer unit to the negative primary terminal of the coil and the black lead to good ground.
3. Turn selector switch to the appropriate cylinder position.
4. Start engine and run until operating temperature is obtained.
5. With engine at normal operating temperature (off fast idle), momentarily open the throttle and release to make sure there is no bind in the linkage and that idle speed screw is against its stop.

Carburettor Switch:

6. On vehicles equipped with a carburetor switch, connect a jumper wire between the carburetor switch and ground. Disconnect and plug the vacuum line at the Spark Control Computer.
7. Read engine RPM on 1000 rpm scale. If the engine rpm is at or below the curb idle specified on the label, proceed to the next step. If it is higher, turn the idle speed screw (on top of solenoid) until the specified curb idle rpm is reached.

Adjustable Timing Lamp:

Timing Marks:

8. Aim Power Timing Lamp at timing hole in bell housing or read magnetic timing unit. If flash occurs when timing mark is before specified degree mark, timing i advanced. To adjust, turn distributor housing in direction of rotor rotation. If flash occurs when timing mark is after specified degree mark, timing is retarded. To adjust, turn distributor housing against direction of rotor rotation. If timing is within + or - 2° of value specified on the label proceed to step 10. If outside specified tolerance proceed to next step,

Distributor Hold Down:

9. Loosen distributor hold-down arm screw just enough so the distributor housing can be rotated in its mounting. Turn distributor housing until specified label value is reached. Tighten the hold-down arm screw and recheck timing. When timing is acceptable, recheck curb idle rpm. If engine rpm is not at or below the curb idle rpm shown on the label, reset engine rpm and recheck timing. Repeat above until both engine rpm and timing are acceptable.
10. Remove timing lamp. Unplug and reconnect the vacuum hose to the SCC unit. If an idle speed adjustment is being perform refer to the procedure. If not, proceed to next step.
11. If curb idle speed is not within - or + 50 rpm of value shown on label, readjust curb idle rpm. Do not reset timing.
12. Turn engine off. Remove the jumper wire, and tachometer.