Ignition Timing
NOTE:
Engines are equipped with a receptacle for magnetic probe timing, 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 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, and distributor vacuum line (if equipped) disconnected and plugged. Light duty models with automatic transmission should be checked in Drive; all others in Park or 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 |
| Calif. |
N/A |
6 @ 550 |
| Federal |
4 @ 700 |
4 @ 550 |
| 5.7L |
| Light Duty |
| Calif. |
N/A |
6 @ 550 |
| Federal |
8 @ 700 |
8 @ 550 |
| Heavy Duty |
| Calif. |
6 @ 700 |
6 @ 700 |
| Federal |
4 @ 800 |
4 @ 700 |
| 7.4L |
| Calif. |
4 @ 700 |
4 @ 700 |
| Federal |
4 @ 800 |
4 @ 700 |