Installation Procedure

NOTE: It is important to check the gap of all new and reconditioned spark plugs before installation. Pre-set gaps may have changed during handling. Use a round wire feeler gauge to be sure of an accurate check, particularly on used plugs. Installing plugs with the wrong gap can cause poor engine performance and may even damage the engine.

Gap the spark plugs to the specifications. Refer to Ignition System Specifications .

Fig 1: Identifying Spark Plug & Wire

Courtesy of GENERAL MOTORS CORP.

NOTE: Be sure plug threads smoothly into cylinder head and is fully seated. Use a thread chaser if necessary to clean threads in cylinder head. Cross-threading or failing to fully seat spark plug can cause overheating of plug, exhaust blow-by, or thread damage. Follow the recommended torque specifications carefully. Over or under-tightening can also cause severe damage to engine or spark plug.

NOTE: Refer to Fastener Notice in Cautions and Notices.

Install the spark plugs.
Tighten: Tighten the spark plugs.
- If the spark plugs are installed into a NEW cylinder head, tighten the spark plugs to 20 N.m (15 lb ft).
- If the spark plugs are installed into an existing cylinder head, tighten the spark plugs to 15 N.m (11 lb ft).
Install the spark plug wires to the spark plugs. Refer to Spark Plug Wire Replacement .
If you are replacing the engine right bank (rear) spark plugs, return the engine to the proper position. Refer to Rotating the Engine for Service Access in Engine Mechanical - 3.4L.