Gather the correct spark plug gap specification for your vehicle or engine
Use a spark plug gap tool or feeler gauge
Check the current gap between the center electrode and ground electrode
Compare the gap to the specified measurement
If the gap is too small, gently bend the ground electrode outward
If the gap is too large, gently bend the ground electrode inward
Recheck the gap after each adjustment
Repeat until the gap matches the specification
Avoid bending the center electrode
Handle iridium and platinum plugs carefully
Install the spark plug once the gap is correct