A GM 3400 is a V6 engine that is commonly installed in GM cars. This engine has six spark plugs installed in it. The manufacturer-recommended spark plug is NKG. There are three spark plugs on each side of the engine in the center. There are no objects blocking the spark plugs, which makes this process a lot simpler than with many other engines. This job will take you around 20 minutes to complete and you can do it in your driveway.
Place the edge of the spark-plug gapper between the metal arm and the pin on the tip of one new spark plug. Turn the gapper so that the number .060 is in the center of the metal arm on the tip of the spark plug. Repeat this for all of the new spark plugs.
Remove one wire form one of the spark plugs on the engine. Place the spark-plug removal tool onto the spark plug and turn the tool in a counterclockwise motion to remove the spark plug. Insert a new spark plug into the hole where the old plug was.
Hand-tighten the spark plug to avoid cross-threading. Then, tighten the new spark plug using the torque wrench and spark-plug socket. Tighten the new spark plug to 11 ft-lbs. Replace the wire to the new spark plug and repeat for all other spark plugs.
