Generac — Adjusting Valve Clearance GH-410/GT-530/990/999
Adjustments · Valve train
From a Generac owner's manual — check it applies to your exact model before use.
Applies to: Generac GH-410 engine, Generac GT-530 engine, Generac GT-990 engine, Generac GT-999 engine
Before you start
- Check valve clearance after first six (6) months of operation.
Procedure
- Engine should be cool before checking; clearance 0.002-0.004 inch needs no adjustment.
- Remove spark plug wires and spark plugs.
- Set piston at Top Dead Center of its compression stroke.
- Remove four screws attaching the valve cover.
- Loosen rocker jam nut; turn pivot ball stud with 10mm allen wrench.
- Set clearance to 0.002-0.004 inch (0.05-0.1 mm).
- Hold pivot ball stud and tighten jam nut to 174 in/lbs torque.
- Install new valve cover gasket and re-attach valve cover.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Valve clearance 0.002-0.004 inch (0.05-0.1 mm)
- Jam nut torque 174 in/lbs
- Engine at 60 to 80 °F
Source: Generac owner's 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.