General Motors 8.1 — Spark Plug Replacement
Maintenance
For the General Motors 8.1, from the General Motors service manual.
Applies to: General Motors 8.1L engine
Procedure
- Remove the spark plug wires.
- Loosen each spark plug one or two turns.
- Brush or air blast away any dirt from around the spark plugs.
- Remove the spark plugs one at a time and place each in a tray marked with cylinder numbers.
- Properly position each spark plug washer.
- Inspect each spark plug gap; adjust as needed.
- Install the spark plugs.
- Install the spark plug wires.
Specs & values
- Spark plug gap: 1.524 mm (0.060 in).
- For iron head all subsequent installations, tighten the spark plugs to 20 N·m (15 lb ft).
- For new iron heads, tighten the spark plugs to 30 N·m (22 lb ft).
Source: General Motors 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.