Ignition Timing
NOTE:
Engines are equipped with a receptacle for magnetic probe timing lights, located 10° ATDC. Do not use this location for timing with a conventional light.
- Connect an adapter between No. 1 spark plug wire or use an inductive type pick-up. Do not puncture wires. Connect timing light according to manufacturer's instructions.
- Check or adjust ignition timing with engine at normal operating temperature, distributor vacuum line (if equipped) disconnected and plugged. Light duty models with automatic transmission should be in Drive; all others in Neutral.
- On California Models with HEI-EST and HEI-ESC distributors, disconnect 4-wire plug connector at distributor when checking ignition timing. Once timing has been set, reconnect connector and clear trouble code from computer.
IGNITION TIMING SPECIFICATIONS (DEGREES BTDC @ RPM)
| Application |
Man. Trans. |
Auto. Trans |
| 5.0L |
| Federal |
4 @ 700 |
4 @ 550 |
| Calif. |
N/A |
6 @ 550 |
| 5.7L |
| Light Duty |
| Federal |
8 @ 700 |
8 @ 550 |
| Calif. |
N/A |
6 @ 550 |
| Heavy Duty |
| Federal |
4 @ 800 |
4 @ 700 |
| Calif. |
6 @ 700 |
6 @ 700 |
| 7.4L |
4 @ 700 |
4 @ 800 |