Cummins/Onan NH-MS/1 / NH-S/1 — Ignition Timing Check — Engine Running
Adjustments · Ignition system
For the Cummins/Onan NH-MS/1 / NH-S/1, from the Cummins/Onan service manual.
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Procedure
- Connect the timing light according to its manufacturer's instructions (either spark plug may be used).
- Place a white chalk or paint mark on the 22° timing mark.
- Start the engine and check the timing; the TC mark should line up with the 22° mark.
- Loosen the breaker box mounting screws and move left to advance or right to retard the timing.
- Start the engine to be sure the TC mark lines up with the 22° mark.
- Tighten all screws and replace the timing plug, breaker box cover and other hardware.
Tools required
- Timing light Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Spark advance 22° BTC
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.