Cummins/Onan — Ignition Timing Continuity Test

Testing & diagnosis

From a Cummins/Onan service manual — check it applies to your exact model before use.

Applies to: Cummins/Onan NHC-NHCV engine

Procedure

1. Adjust breaker points.
2. Remove air intake hose or cylinder shroud to expose timing marks.
3. Rotate flywheel clockwise until timing mark aligns with 20° BTC mark on gearcase cover.
4. Connect ohmmeter or continuity test lamp across ignition breaker points.
5. Touch one test prod to coil lead terminal and other to good ground.
6. Turn crankshaft counterclockwise until points close, then slowly clockwise.
7. Lamp should go out just as points break.
8. If timing early, point gap too large; if late, too small. Adjust accordingly.

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.

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