Compression Tester adapter size ?

[Aok]

I would like to do a compression test but need a adapter to fit my tester. I know the vendors sell one but do not need anything right now and would like to do this in the next day or so as I am in the process of doing a tune.
Anyone know what size bushing I need to fit the model a spark plug hole.

[Colorado Greg]

Spark plug hole size is 7/8-18. You could also use an old plug, gut it and tap it to the size you need.

[glenn in camino]

I replaced the small rubber sealer on the end of the compression guage with one I made out of a rubber bushing that I think came from a modern shock absorber. Works good.

[Aok]

Thanks 2 good suggestions I will see what I can come up with

[Kurt in NJ]

I have used an old sparkplug and for the tester thread I use a "anti-fowler ---braze them together ----I guess JB weld or such would work too if there is enough surface glued but it wouldn't be as reliable as brazing or welding

[Popeye31]

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My compression gadge has a quick disconect like a air hose I gutted a sparkpluge and welded a fiting that will go on my compression gadge works great.

[fordfixer]

If you can get your hands on the spark plug adaptor for modern 18 mm. plugs, the compression gauge should screw right into it. This is what I use.

[BILL WILLIAMSON]

I have a cheap, old hand held tester, and it's rubber cone is plenty big for the 7/8" plug holes. Bill W.

[ABento]

I have checked at napa and have not found an adapter for the 18 MM plugs such as John Deere or International use, and I believe that the "A" plug is 7/8 x 18 not 18 MM, I asked here about an adapter and Branten sells them for 6.50

It seems I missed the post by Ford fixer, I was under the impression that the 7/8 x 18 was not in MM.

[fordfixer]

Sorry if I had the 18 mm part wrong. I was in a rush last night. The parts houses sold a adaptor for using the modern plugs. This is the one I meant for you to use. They also are good for making and engine lift bolt.

[Purdy Swoft]

Lots of the model A parts houses sells a 7/8 x18 adapter for useing modern 14MM spark plugs in the model A. The adapter will need 7/8X18 threads to thread into the head. The threads on my compression tester is 14 MM. I use the modern spark plug adapter from Snyder with my compression tester. 7/8X18 to 14 MM

[1928Pickuppain]

Take plug gut it and solder it to the end of yours that's how I did mine works pissa

[CarlG]

What Purdy said!

I went ahead and bought a package of 4 to save a few bucks. I have one on my compression tester, put one on my leak down tester, and my fellow Model A'ers have snapped up the others.

[Aok]

I have solve my problem with a old tool I forgot I had, I was looking for a gauge with the rubber base like BILL WILLIAMSON had suggested in a earlier post when I found a old mechanical compression tester I picked up somewhere years ago. The reads were 50, 50, 45,50 which I think is ok.
I 1st used the base to connect to my new tester then used the old mechanical tester readings were about the same