Generac — Set or Replace Spark Plugs
Adjustments · Ignition system
From a Generac owner's manual covering: 4.6L 80kW, 5.4L 100kW, 6.8L 130kW, 6.8L 150kW, QT 6.8L 100kW. Check it applies to your exact model before use.
Applies to: Generac QT 6.8L 100kW, Generac V-type engine
Before you start
- Do not blast the spark plugs to clean.
Parts for this job
- RC12LC4 Spark plug Amazon eBay $26.61
Part numbers from the service-parts list for Generac QT 6.8L 100kW. Verify against your serial number before ordering; some links are affiliate links.
Procedure
- Clean the area around the base of the spark plugs to keep dirt and debris out of the engine.
- Remove the spark plugs and check the condition. Replace if worn or if reuse is questionable.
- Check the spark plug gap using a wire feeler gauge.
- Adjust the gap to 1.14 mm (0.045 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 1.14 mm (0.045 inch)
Full service-parts list: Generac QT 6.8L 100kW →
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.