Cummins/Onan — Valve Clearance Adjustment (Two-Cylinder J-Series)
Adjustments · valve train
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Procedure
- Turn flywheel until cylinder to be adjusted is on its compression stroke, following closing of the intake valve.
- Turn flywheel until TC mark on flywheel lines up with timing pointer on gear cover.
- Turn flywheel clockwise an additional 10 to 45 degrees.
- Using a feeler gauge, check clearance between rocker arm and valve.
- Increase or reduce clearance until proper gap is established; adjust with lock nut securing rocker arm to cylinder head.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Refer to Specifications for correct valve clearance
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.