With a Honda spark plug operating correctly in each cylinder of your vehicle, you will enjoy a smooth running engine. In the ignition system on your car, this is the primary component that ignites the air and fuel mixture in the combustion chamber. Without this small little arc of electricity, your internal combustion engine could not operate. One of the most overlooked settings on a Honda is the gap of the spark plug. Many owners think this ignition component has the gap set at the factory. This is only true for the first set of spark plugs your Honda has in it when it is new. Every set that is used in a tune-up must be set before the new plugs are installed in the engine. The gap of the Honda spark plugs is measured with a feeler gauge. Each Honda engine as a specific gap and that must be known by the person installing the new plugs. With this measurement in mind, the feeler gauge is then pulled through the gap opening. You know this gap is correct when the resistance on the feeler gauge is only slight. Most owners and technicians perform this step of a tune-up all at once. This makes it possible to establish the gap in all of the spark plugs as close to one another as they can be. The gap is the open area of the plug between the electrode at the end of the spark plug and the metal bar that is fitted above it. This is the space where the electricity will pass, and is where the air and fuel mixture is actually ignited at the top of the combustion chamber. With all of the gaps the same in your Honda, a smooth running engine is possible.