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Generac — Valve Adjustment

Adjustments · Rocker arms / valves

From a Generac service manual covering: GPS 12500, GPS 15000, GPS 17500. Check it applies to your exact model before use.

Applies to: Generac GPS 12500, Generac GPS 15000

Procedure

  1. Adjust valve clearance with engine at room temperature.
  2. Position piston at top dead center of compression stroke (both valves closed).
  3. Loosen rocker arm jam nut; use 10mm allen wrench to turn pivot ball stud.
  4. Check clearance between rocker arm and valve stem with feeler gauge.
  5. Hold pivot ball stud; tighten rocker arm jam nut to 168 inch-pounds (19 Nm).
  6. Recheck valve clearance after tightening jam nut.
  7. Install rocker arm cover with new gasket; retain with four screws.

Tools required

Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.

Specs & values

  • Intake 0.002-0.004 inch (0.05-0.1 mm)
  • Exhaust 0.002-0.004 inch (0.05-0.1 mm)
  • Rocker arm jam nut 168 inch-pounds (19 Nm)

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.

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