Thumbs 1
Thumbs 1

Heavy Duty Spark Plug Gapper Kit

Add to Wishlist
Part# 12-03359
MFR Model# ATS420DX


A complete spark plug gapping solution for field or bench use includes the Heavy Duty Spark Plug Gapping Tool to accurately set your spark plug gaps to within 0.001". You also get a set of wire feeler gauges to verify gap size. If you should happen to accidentally over-gap the plug, then the included Gap Expansion Tool will get you back on track. And finally, included in the Kit is an Electrode Erosion Gauge to make sure that your gapped plugs are still in serviceable condition.


  • Sets gaps to within 0.001"
  • Compatible with all Champion, and AutoLite Massive Electrode Spark Plugs

In The Box

  • Gapping Tool
  • Feeler Gauge
  • Erosion Gauge
  • Gap Expansion Tool
  • Frequently Purchased With
  • Customers Also Viewed
  • Related Items


This spark plug gapper tool and the gap gauges make it easy to check and set the gap correcty for aircraft spark plugs.

Joseph A
March 17, 2021

This is a nice kit. It is a little expensive for what you get, but everything is very nicely made and quite heavily constructed - heavier than I expected it to be.

Michael V
April 16, 2020

Not used yet but first impressions are very positive. Looks well built and was well packaged.

Glen B
June 11, 2017

It works. However, the wire gauge is made from cheap plastic. The rest of the kit is quality made.

January 11, 2021


Please note, Aircraft Spruce's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Aircraft Spruce assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.

Q: Will this set work with Tempest UREM37BY spark plugs?

Yes, this would work with all Tempest and Champion aviation spark plugs.

Q: Will this Heavy Duty Spark Plug Gapper Kit work with 14 and 18mm plugs?

Works with 18MM spark plugs only.

View in Catalog

View Image View in Catalog