Cummins/Onan — Ignition Timing Check - Engine Running
Adjustments
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan NHC-NHCV, Cummins/Onan NHC-NHCV engine
Procedure
- Connect timing light per manufacturer instructions.
- Start engine and check timing at idle.
- Pointer on flywheel should line up with 25° mark on cover.
- If marks do not line up, readjust point gap.
- To advance timing, slightly open breaker point gap.
- To retard timing, slightly close breaker point gap.
- Recheck timing and point gap.
Tools required
- Timing light Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Timing 25° BTC
Full service-parts list: Cummins/Onan NHC-NHCV →
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.