Spark plugs are those all important components of an engine's ignition system that deliver spark to the engine. The plugs thread into the heads. The ends of the plugs protrude into the combustion area above the cylinders. When the spark from the plug combines with the air and fuel, the result is an explosion (internal combustion) that forces the cylinder down. Bosch is one of the most respected manufacturers of spark plugs. A spark plug's gap can affect how well a car runs.
Determine what the recommended spark plug gap is for your vehicle. You can use a workshop manual that will give you the factory specifications. You may also be able to get the specs from the vendor that you sourced the spark plugs from.
Remove the spark plugs from the engine with a spark plug wrench. If you are installing new spark plugs, remove them from the boxes and lay them all out on a rag or work area.
Slide the spark plug gapping tool between the center electrode of the plug and the ground electrode until the distance between the two corresponds with the gap you are setting the plugs at. The tool should fit firmly between the spark plug's electrodes at the proper gap indicated by the numbers on the tool.
Tap the end of the spark plug lightly if you need to reduce the gap. This will bend the electrode down a little. You do not have to tap very hard, just enough to bend the metal slightly. Tap the plug on something hard, such as concrete. Slide the gapping tool back in until the proper gap is achieved.
