The thread size is a 14 X 1.25 (14 millimeter diameter by 1 thread every 1.25 millimeters.
This is not a common thread size other than spark plug use.
I think your 90* adaptor is a good idea, but it would take some doing to make it work properly. The biggest thing would be to make the female thread swivel around 360* once the adaptor is installed and sealed to the head. This way you could swivel the threaded hole (where you actually hook up the compression tester) to any position you want, so it won't possibly be pointing at an obstruction.
Ron
|