Generac — Check and Adjust Valves
Adjustments · Engine valve train
From a Generac service manual — check it applies to your exact model before use.
Applies to: Generac GH-410 engine, Generac GT-530 engine, Generac GT-530 engine, Generac GT-990 engine
Procedure
- Make sure that the piston is at Top Dead Center (TDC) of its compression stroke (both valves closed).
- Remove the four (4) screws from the rocker cover.
- Remove the rocker cover and rocker cover gasket.
- Loosen the rocker arm jam nut and use a 10mm allen wrench to turn the pivot ball stud.
- Check the clearance between the rocker arm and the valve stem with a flat feeler gauge.
- When the valve clearance is correct, hold the pivot ball stud with the allen wrench and tighten the rocker arm jam nut.
- Recheck the valve clearance to make sure it did not change.
- Re-install the rocker cover gasket, rocker cover and the four (4) screws.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Valve clearance should be 0.05-0.1mm (0.002-0.004 in) cold.
- Torque the jam nut to 174 inch pounds.
Source: Generac 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.