Proper Gapping Instructions

If it is necessary to widen the gap, do so with a tool that only pulls back on the ground electrode without touching the center electrode or the porcelain. To close the gap on a plug, gently tap the plug, electrode first on a hard surface.

Spark plug manufacturers don't recommend adjusting the plug gap more than .008" in either direction. Beyond that slight adjustment, the ground electrode and center electrode won't align properly, hindering spark plug performance and drastically reducing plug life. Pulse plugs can be adjusted beyond this recommendation, but should never be opened to more than .055”.