Spark Plugs: Installation

NOTE: Use only the spark plugs specified for use in the vehicle. Do not install spark plugs that are either hotter or colder than those specified for the vehicle. Installing spark plugs of another type can severely damage the engine.

NOTE: Check the gap of all new and reconditioned spark plugs before installation. The pre-set gaps may have changed during handling. Use a round feeler gage to ensure an accurate check. Installing the spark plugs with the wrong gap can cause poor engine performance and may even damage the engine.

Measure the spark plug gap on the spark plugs to be installed. Compare the measurement to the gap specifications. Adjust each plug as needed. See SPARK PLUGS under IGNITION SYSTEMS in appropriate SERVICE & ADJUSTMENT SPECIFICATIONS article.
NOTE: Be sure that the spark plug threads smoothly into the cylinder head and the spark plug is fully seated. Use a thread chaser, if necessary, to clean threads in the cylinder head. Cross-threading or failing to fully seat the spark plug can cause overheating of the plug, exhaust blow-by, or thread damage.
Install the spark plugs to the engine. See Fig 1. Tighten the spark plugs to specification. See TORQUE SPECIFICATIONS .
Install the ignition coils. See IGNITION COILS .

Fig 1: Removing & Installing Spark Plugs

Courtesy of GENERAL MOTORS CORP.

Properly position each spark plug washer. Inspect each spark plug gap. Adjust each plug as needed. See SPARK PLUGS under IGNITION SYSTEMS in appropriate SERVICE & ADJUSTMENT SPECIFICATIONS article. Hand start the spark plugs in the corresponding cylinders. Tighten the spark plugs to specification. See TORQUE SPECIFICATIONS .