Compression Tester adapter size ?

Aok

Aok

Well-known member
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.
 
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.
 
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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.
 
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
 
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.
 
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.
 
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.
 
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.
 
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
 
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.
 
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

Comprission_Gauge.jpg




Comprission_Gauge1.jpg
 
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