Cummins/Onan — Time ignition, MJC (engine stopped)
Adjustments
From a Cummins/Onan service manual covering: 10MJC, 15MJC, 3MJA, 4MJA, 5MJB, 705MJB. Check it applies to your exact model before use.
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Procedure
- Disconnect low voltage lead to distributor.
- Connect test lamp so it lights when points closed.
- Remove #1 spark plug.
- Rotate flywheel clockwise until air escapes #1 cylinder.
- Continue slowly until lamp goes out.
- Align flywheel TC mark with timing pointer.
- If incorrect, loosen distributor body and rotate until lamp goes out.
- Retighten distributor and recheck.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- TC mark alignment
Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.