The Universal Spark Plug Gap Tool with Feeler Gauge is the perfect addition to your tool box and essential when gapping spark plugs for performance. Properly gapped spark plugs are critical for a well tuned car; too much gap can blow away the spark and too little gap can waste it. 

Gapping a spark plug with this tool is simple - just place the spark plug in the gap tool and turn the knob with the appropriately-sized feeler gauge in place until the side electrode is compressed to the required gap thickness.

It's important to note that some spark plugs may have a ground strap that springs back, which is normal. To achieve a gap target of 0.44mm, it is recommended to use a 0.42mm feeler gauge - this way, when the electrode springs back, it will rest at the desired gap thickness.

The Universal Spark Plug Gap Tool with Feeler Gauge provides dual markings for both metric and imperial measurements, ranging from 0.0015"/0.04mm to 0.035"/0.88mm.