Cummins/Onan — Ignition Timing Adjustment

A Cummins/Onan service procedure — check it applies to your exact model before use.

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Procedure

1. Shift the whole breaker box assembly to the right (with crankshaft rotation) to advance the timing (points not breaking soon enough) or to the left to retard the timing (points breaking too soon).
2. The witness marks on the cylinder block and breaker box may not be in alignment after this adjustment has been made but this is not important as these marks give only an approximately correct position of the breaker box.
3. Tighten the breaker box mounting screws securely after making an adjustment.
4. Replace the breaker box cover.

Source: manual:910-1028 Onan CK Industrial Engine Instruction Manual (5-1964).pdf. Figures and steps are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.