Cummins/Onan 305CCK / 5CCK — Ignition Timing
Adjustments · Ignition breaker
For the Cummins/Onan 305CCK / 5CCK, from the Cummins/Onan operator's manual.
Applies to: Cummins/Onan 5CCK
Before you start
- Use only a 6-volt coil tester.
Procedure
- Remove breaker box cover; align witness marks approximately if timing is far off.
- Crank engine slowly by hand in crankshaft rotation until flywheel witness mark aligns with TC mark on gear cover.
- Set breaker point gap to 0.020 inch at full separation.
- Turn flywheel to left about two inches past 25° mark on gear cover.
- Turn flywheel slowly right and check points separate when flywheel mark aligns with correct 19° or 25° mark.
- Shift breaker box toward air cleaner to retard or away to advance; tighten mounting screws.
- Reinstall breaker box cover.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Spark advance 19° before top center for 1500 to 2400 rpm; 25° for 2500 rpm and up.
- Breaker point gap 0.020 inch at full separation.
Full service-parts list: Cummins/Onan 5CCK →
Source: Cummins/Onan operator's 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.