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Generac 005222-0 / QT 3.9L 40kW — Spark Plugs - Inspection and Gap Adjustment

Adjustments

For the Generac 005222-0 / QT 3.9L 40kW, from the Generac owner's manual.

Applies to: Generac QT 3.9L 40kW, Generac V-type engine

Parts for this job

Part numbers from the service-parts list for Generac QT 3.9L 40kW. Verify against your serial number before ordering; some links are affiliate links.

Procedure

  1. Clean area around base of the spark plugs using a wire brush and commercial solvent; do not blast the plugs.
  2. Remove the spark plugs and check condition; replace if worn or reuse is questionable.
  3. Check spark plug gap using a wire feeler gauge.
  4. Adjust gap to 1.01 mm (0.040 inch) by carefully bending the ground electrode.

Tools required

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

Specs & values

  • Spark plug gap 1.01 mm (0.040 inch)

Full service-parts list: Generac QT 3.9L 40kW →

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.

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