Cummins/Onan — Timing Ignition (Engines Without Spark Advance Mechanism)
Adjustments · ignition/breaker box
From a Cummins/Onan service manual covering: 4CCK, 5CCK, 5CCK-150R, 5CCK-3CR. Check it applies to your exact model before use.
Applies to: Cummins/Onan 4CCK, Cummins/Onan 5CCK, Cummins/Onan CCK engine
Before you start
- Do not use 12-volt coil tester; use 6-volt tester
Procedure
- Remove the cover from the breaker box.
- Shift breaker box to align witness marks on cylinder block and breaker box.
- Crank engine slowly until flywheel witness mark and TC mark on gear cover align.
- Set breaker point gap to .020 in. at full separation.
- Turn flywheel left about two inches past the 25 degree mark.
- Turn flywheel slowly right and note if points just separate at 19 or 25 degree mark.
- Shift breaker box toward #1 cylinder to retard, away to advance.
- Tighten breaker box mounting screws and reinstall cover.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Breaker point gap 0.020 in.
- 19 degrees BTC (1500 to 2400 rpm); 25 degrees BTC (2500 rpm and up)
Full service-parts list: Cummins/Onan 4CCK →, Cummins/Onan 5CCK →
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.