Cummins/Onan B43 / B48 — Ignition Timing Continuity Test
Testing & diagnosis · ignition system
For the Cummins/Onan B43 / B48, from the Cummins/Onan service manual.
Applies to: Cummins/Onan B48
Procedure
- Adjust breaker points.
- Remove blower housing to expose timing marks on top of gearcase cover and flywheel.
- Rotate flywheel clockwise until timing mark is aligned with the proper number of timing degrees stamped on top of gearcase cover.
- Connect an ohmmeter or continuity test lamp across the ignition breaker points; one prod to coil lead terminal, other to a good ground.
- Turn crankshaft counterclockwise until points close, then slowly turn clockwise.
- Lamp should go out or continuity lost just as points break.
- If timing is early (advanced) point gap is too large; if late (retarded) point gap is too small; adjust accordingly.
Tools required
- ohmmeter or continuity test lamp Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Static ignition timing 21 deg BTDC (both models)
Full service-parts list: Cummins/Onan B48 →
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.