Cummins/Onan WC4-10S-5 — Governor and Modutrol Adjustment
Adjustments · Governor and Modutrol motor
For the Cummins/Onan WC4-10S-5, from the Cummins/Onan service manual.
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Before you start
- Care should be exercised to avoid disturbing or changing the adjustment of the governor-to-Modutrol motor connecting link.
Procedure
- With spring tension on main governor spring (A), adjust governor-to-carburetor control link so carburetor lever clears the wide open stop by at least 1/64 inch.
- Screw bumper screw (B) out far enough that it does not function.
- Start engine, press decrease frequency control switch to run at reduced speed, and allow normal operating temperature.
- Place a lead jumper on terminals 5 and 6 so the Modutrol motor travels to its full limit in the frequency increasing direction.
- See that the ball end of the Modutrol arm points to the rear and is slightly below center; if not, reset the arm.
- Adjust the governor-to-Modutrol connecting link to a length that provides an output frequency of 65 cycles.
- Move the jumper to terminals 4 and 5 (frequency decreasing direction); frequency should be about 55 cycles.
- If the governor surges under load, screw auxiliary adjusting screw (D) out a few turns at a time until surging stops.
- If the governor surges without load, screw in bumper screw (B) until surge is eliminated and tighten lock nut.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Output frequency 65 cycles (increase limit)
- About 55 cycles (decrease limit)
- Carburetor lever clears wide open stop by at least 1/64 inch
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.