Generac — Adjusting Valve Clearance

For these Generac models: 004666, 004666-1, 005011, 005011-0, Model 004666, Model 005011.

Applies to: Generac Model 004666, Generac Model 005011

Procedure

1. Make sure the engine is at room temperature.
2. Make sure that the spark plug wire is removed from the spark plug and out of the way.
3. Remove the four screws attaching the valve cover with a #2 or #3 phillips screwdriver.
4. Make sure the piston is at Top Dead Center (TDC) of its compression stroke by rotating the engine via the flywheel nut.
5. Loosen the rocker jam nut.
6. Use a 10mm allen wrench to turn the pivot ball stud while checking clearance between the rocker arm and the valve stem with a feeler gauge.
7. Correct clearance is 0.002-0.004 inch (0.05-0.1 mm).
8. When valve clearance is correct, hold the pivot ball stud in place with the allen wrench and tighten the rocker arm jam nut to 174 in/lbs torque.
9. After tightening the jam nut, recheck valve clearance to make sure it did not change.
10. Install new valve cover gasket.
11. Re-attach the valve cover.
12. Re-attach the spark plug wire to the spark plug.
13. Repeat the process for the other cylinder.

Source: manual:centurion_manual.pdf. Figures and steps are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.