Compression Tester Gauge

[mud pie]

My original compression tester is shot, and I mean SHOT. face broken, line cracked up, spark plug fitting no where to be seen..

In 1979 at age 18 when I joined the Marine Corps, my parents moved to Texas.  Bekins Moving boxed everything up, apparently hamfisted, or my dad or sisters broke it.  Now granted, it's been a few years since I went there to look at it.....

But all I can find now on the market is testers with adapters in millimeters    What about us that still have SAE ??  Anybody have a source ?  

[Carls_jeep]

I think all the spark plugs except for some of the very earliest are metric. Try a google for spark plug thread sizes.

You can take what is left of your set and use a spark plug and an air fitting that fits your set to make any adapters you need. Just bust the porcelain core out, thread the metal part and insert the air fitting.

[mud pie]

I think all the spark plugs except for some of the very earliest are metric. Try a google for spark plug thread sizes.

You can take what is left of your set and use a spark plug and an air fitting that fits your set to make any adapters you need. Just bust the porcelain core out, thread the metal part and insert the air fitting.

Thanks !!  I did a Google search (what did we do before Google ? Ask a neighbor ? Go to (gasp !) the library ??), turns out the threads are 14mm.   Makes getting a compression tester all that much the easier.

[Doug]

I believe the metric ones also fit the us threads.   I believe my compression gauge has metric size plug adapters but that they fit the standard spark plug sizes.  In other words, what I am trying to say is that they are expressing the adapter size in metric terms but it still fits the same old standard spark plugs.  Does that make sense.  

[Carls_jeep]

Yes because the spark plugs are metric. As far as I have found out there were several thread sizes used in the late 1800's and early 1900's. Ford used a 1/2 NTP thread in the Model T and another popular thread was the 7/8-18. As time passed metric threads won over and I doubt you'll find any engines made after the 1930's using anything but metric.