Generac — Valve Lash Adjustment
Adjustments · engine
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
- Contact the Dealer for service assistance
Procedure
- Remove spark plug wires and spark plugs
- Rotate flywheel nut clockwise to bring piston to TDC of compression stroke
- Ensure engine is at 60-80°F (16-27°C)
- Remove the four screws attaching the valve cover
- Loosen rocker jam nut, turn pivot ball stud while checking clearance with a feeler gauge
- Adjust to 0.002-0.004 in (0.05-0.1mm) clearance
- Hold pivot ball stud and tighten rocker arm jam nut to 174 in-lbs (19.68 N-m)
- Recheck valve clearance after tightening
- Install new valve cover gasket and reattach valve cover
- Install spark plugs and reattach spark plug wires
Tools required
- 10mm Allen wrench (530cc engine) or 13mm Allen wrench (410cc, 990cc, 999cc engines) Amazon
- Feeler gauge Amazon
- Torque wrench Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Clearance 0.002-0.004 in (0.05-0.1mm)
- Jam nut torque 174 in-lbs (19.68 N-m)
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.