Cummins/Onan NH-MS/1 / NH-S/1 — Breaker Point Replacement and Gapping

Maintenance · Ignition breaker points

For the Cummins/Onan NH-MS/1 / NH-S/1, from the Cummins/Onan service manual.

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Procedure

1. Remove the two screws and the cover on the breaker box.
2. Remove the two spark plugs so the engine can be easily rotated by hand.
3. Remove the breaker point mounting screws and install a new set; leave the screws loose.
4. Rotate the engine clockwise by hand until the flywheel mark and TC mark on the gear cover align.
5. Turn the points adjusting cam screw until the point gap is .020 in, then tighten the mounting screws.
6. Turn the flywheel to the left past the timing marks, then turn to the right.
7. Points should separate when the flywheel TC mark aligns with the correct degree mark.

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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