My Willys 3A and 3B Community

3A, 3B, DJ Technical Knowledge Base => "Original"-- Technical Questions, Answers, Observations => Topic started by: athawk11 on January 05, 2014, 11:18:45 PM

Title: Spark Plugs...Millimeter???
Post by: athawk11 on January 05, 2014, 11:18:45 PM: I have replaced the plugs in a few Willys Jeeps, but have never really paid attention to the thread size.ï¿½ They have always fit, so, no worries.

I need to pick up an engine compression tester and want to get one with the proper connection.ï¿½ I am led to believe the plug size in our Willys have MM threads.ï¿½ Is that correct? :o

Tim
Title: Re: Spark Plugs...Millimeter???
Post by: scoutpilot on January 06, 2014, 03:55:53 AM: Not metric that I am aware of. Go to NAPA and ask for the 'good' compression tester. It will have adapters, but worked for me on both the L and F heads straight out of the box.
Title: Re: Spark Plugs...Millimeter???
Post by: garage gnome on January 06, 2014, 08:32:26 AM: I think 18mm is the metric equivalent.
Title: Re: Spark Plugs...Millimeter???
Post by: 1955CJ-5 on January 06, 2014, 01:05:11 PM: The spark plugs are 14mm...

I bought an Innova Equus #3612 tester and it comes with adapters for 12, 14 and 18 mm.

I don't remember where I got it, but it told me what I wanted to know!

And so why are they metric...? The early manufacturer of the spark plug, Albert Champion, was French.....

The Innova tester has instructions in three languages, including French, so it must be good!
Title: Re: Spark Plugs...Millimeter???
Post by: SteveW on January 07, 2014, 01:18:34 AM: 14mm for sure. I made the mistake of trying to Americanize one of mine and had to fix it with insert kit.
Title: Re: Spark Plugs...Millimeter???
Post by: gmcjr on January 13, 2014, 05:12:24 AM: Quote
The spark plugs are 14mm...

And so why are they metric...? The early manufacturer of the spark plug, Albert Champion, was French.....

Thanks! Was always curious!