Cummins/Onan W3M-19 — Timing the Magneto
Adjustments
For the Cummins/Onan W3M-19, from the Cummins/Onan service manual.
Applies to: Cummins/Onan W3M-19, Cummins/Onan W2C engine
Before you start
- Do not crank engine while gear housing is off the magneto
Procedure
- Remove No. 1 spark plug (nearer radiator).
- Hold thumb over plug hole and crank slowly until compression felt.
- Continue cranking until flywheel timing mark aligns with T.C. mark on crankcase.
- Turn magneto gear in normal direction until impulse coupling just trips.
- Distributor arm must point toward No. 1 tower.
- Install magneto gear without turning distributor from position.
- Crank engine slowly and note if coupling trips at timing marks.
- If not, loosen magneto flange cap screws and turn frame slightly.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Spark advance 20 to 25 degrees at normal speed (about 1-1/2 in. on flywheel)
Full service-parts list: Cummins/Onan W3M-19 →
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.