Mac, I do similar all the time. Sometimes I don't look before I leap. Sometimes I misspeak. So I may or may not have a suggestion. My training, which I sometimes forget, is to thoroughly understand the problem. In doing this, a person sounds dumb sometimes. These questions are for anyone to answer.
1. In that picture, that thing with a dial is the gauge, what is that other thing with female threads. Is that the piece you are trying to mate to the gauge?
2. I would expect an old gauge to have pipe threads.
3. Does anyone know the exact size and type of the male threads on the gauge and the exact size and type of threads on the mating female part? It seems unverified. So can't continue until those are known and stated for sure.
4. What is that thing sitting on the glass?
5. Why is the desired gauge, a compression gauge instead of a pressure gauge?
6. You say you picked up a gauge, then say "dump valve" in the same sentence. Which part in the picture is a dump valve?
What is in the picture is a very old engine cylinder compression gauge tool- taken somewhat apart. (
***This may be part of the breakdown on my part because I'm not real knowledgeable when it comes to fittings and proper terminology-) I mentioned above that the threads are 3/8".
the inside hole diameter is 1/8. I got the 3/8" threads part (it measure.565 or 5/8 diameter) from the fact that a standard 3/8 compression male fitting would go in about 1turn and stop. Threads are straight as verified with my calipers with a 27 pitch according the thread gauge. The small round piece sitting on the gauge face is a brass "spacer"(?) with a gasket on top that sits down into the brass body with female threads- then the gauge screws down on top of that gasket making the seal. What is not seen in the picture is the "other end" of the main brass body- which (was) a tapered rubber piece that pressed against the spark plug hole. That rubber piece was pressed on a barbed connection that affixed to the main body somehow.
The reason I'm utilizing this piece is because it's really old and really cool. I want to see the overall system pressure so am using the 200 PSI gauge itself for that. The "Compressometer" name is simply a name (yet another cool factor to me) and will register the approx 120 PSI pressure of the system.
Since I am putting helper bags on the rear and want to have a separate gauge for that. I also need to release the air pressure there (most of it) when not hauling a load so for that I get to use the main brass body portion with the release- we've always generically called them dump valves. I'll never run over 50 PSI for the bags and for that will use another old gauge (1949 R. Perlick Brass Co) which has 1/4" tapered pipe threads (approx 1/2" diameter at the narrow end). That is where the modification takes place- the Perlick gauge with 1/4" male pipe to the original cylinder compression gauge body with straight 27 pitch threads.AND the straight 27 pitch threaded 200 PSI gauge going to a 3/8" compression fitting for the overall system.
Mr. klhansen I think you've started me in the right direction on first of all taking out the check valve at the end of the main body threads to simply drill and then re-thread to a standard thread choice. And also for the link to the buyfittingsonline website. Thanks for that.
Sorry to lead you boys down the rocky trail but once again I appreciate the help and chance to learn more new things to me all the time.
