Cummins/Onan — Adjust Valve Clearance (Two-Cylinder Engine)
Adjustments · Cylinder head / valves
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan DJB engine
Before you start
- Adjust with engine at room temperature (approximately 75F); allow at least two hours cooling
Procedure
- Turn flywheel until the cylinder is on its compression stroke.
- Line up the TC mark on the flywheel with the timing pointer, then turn clockwise an additional 10 to 45 degrees.
- Check the cylinder head bolt torque.
- Using a feeler gauge, check clearance between rocker arm and valve; adjust with the lock nut.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- See Table 4 valve clearances: DJB prior Spec D 0.004 in; DJB begin Spec D intake 0.009 / exhaust 0.007 in; DJC intake 0.009 / exhaust 0.007 in
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.