The following steps explain how to gap your spark plugs:
1Clean your spark plug.
If you’re regapping a pre-owned plug, make sure that it’s clean (gently scrub it using a wire brush). It should be clean and new-looking, with the tip of the side electrode centered over the center electrode, if you’re using a new plug.
You shouldn’t see any cracks or bubbles from the porcelain insulator, and the threads should be unbroken.
2Select the proper number on your feeler gauge, and run the gauge in between the electrodes.
To find the right gauge, look for a spec sheet for the automobile within the owner’s manual, or you can obtain the information from the local auto parts store. If the gauge doesn’t experience, or if it is through too easily without touching the electrodes, you have to adjust the distance between the electrodes.
3Adjust the gap as necessary.
The gap is way too narrow in the event the wire didn’t go through. Hook the area of the feeler gauge that’s used for bending electrodes under the side tug and electrode very gently to widen the gap. A feeler gauge is shown here.
If the gauge passes through too easily without touching the electrodes, the gap is wide. Press the side electrode very gently against a clean, mar-proof surface until it’s slightly bent down toward the center electrode.
4Run the gauge through the gap again.
You want the gauge to endure fairly easily, just catching the electrodes as it passes.
If you keep adjusting the gap too narrow or too wide, don’t feel bad. Most people check out the “too large-too small-too large” bit a couple of times for each and every plug, particularly the perfectionists.