Choosing the Best Spark Plug Gap Tool: A Comprehensive Guide

How to Choose the Best Spark Plug Gap Tool

The best spark plug gap tool uses wire gauges that allow you to see the fit of the spark plug gapper tool between the two electrodes. These are referred to as go, no-go wire feeler gauges. Simply slide the proper wire gauge through the gap. If you see light between the gauge and the electrodes, the gap is too wide. If you feel a slight drag, the gap is right on.

Wire spark plug gappers

Lisle Tools 67800 spark gap tool

.025, .030, .034, .035, .040, .045

Lisle Tools 67900 spark gap tool

.040,, .044, .045, .050, .060, .080

CTA Manufacturing 3238 gap tool

.025, .030, .035, .040, .044, .045, .050, .055, .060″

CTA Manufacturing A326 gap tool

.025, .030, .034, .035, .040, .045″

CTA Manufacturing A328 spark plug gapping tool

.040, .044, .045, .050, .060, .080″

Stanely PROTO J000J spark plug tool

.044″, .045″, .050″, .054″, .060″, .080″.

Gearwrench 164 spark plug  tool

0.025, 0.030, 0.034, 0.035, 0.040, 0.045

The worst spark plug gapper

Unfortunately, the worst spark plug gapper tools are the

worst spark plug gapper

ones sold most often near the cash registers at auto parts stores. The tapered “coin” gauges are responsible for damaging more new spark plugs than any other type. That’s because owners use them to “slide” open the gap, rather than use an electrode bending tool.

The precious metal tips are welded onto the center and side electrodes. As you slide the tapered gapper between the welded tips,  you can break them off, ruining your expensive spark plug. In addition to breaking off the welded tips, the tapered gap tool can also break off the side electrode. Even if the electrode doesn’t break at the moment, you can weaken it to the point where it will break off in use. Don’t use a tapered gapper to enlarge the gap.

If you own one, use it only as a measuring tool, never as a gapper tool.

©, 2021 Rick Muscoplat