Cummins/Onan 3100 series — Adjusting Engine Timing
Adjustments · Ignition system / CD1 Ignition Module
For the Cummins/Onan 3100 series, from the Cummins/Onan service manual.
Applies to: Cummins/Onan GGKD
Before you start
- DO NOT switch from position 7 to 0, or 0 to 7 while the engine is running.
Procedure
- Connect the timing light high tension lead to the No. 1 spark plug (front cylinder).
- Start the genset.
- Point the adjustable timing light toward the pointer and TDC mark on the crank pulley.
- Remove the white plastic cap and turn the timing switch adjustment screw (10 degree range) of the CD1 Ignition Module.
- Switch position 7 gives the most advanced timing; timing retards 1.4 degrees per switch position toward 0 (full retard).
- Allow a short delay between each timing position change.
- Perform the Carburetor Power Valve Adjustment procedure.
Tools required
- Timing light Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- GGKB/GGKC: 28 to 32 degrees BTDC
- GGKD: 26 to 30 degrees BTDC
- Timing retards 1.4 degrees per switch position
Full service-parts list: Cummins/Onan GGKD →
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.