Cummins/Onan — Valve clearance adjustment MJB
Adjustments
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Procedure
- Turn flywheel so piston of valve to be checked is 10 to 45 degrees after TDC of compression stroke.
- Turn flywheel until TC mark lines up with timing pointer, then an additional 10 to 45 degrees clockwise.
- Check cylinder head bolt torque.
- Using a feeler gauge, check clearance between rocker arm and valve.
- Adjust with the locknut securing rocker arm to cylinder head until proper gap is established.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- MJB intake 0.010 in (0.25 mm) cold
- MJB exhaust 0.010 in (0.25 mm) cold
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.