I have to agree with you, Major. Cut threads leave a stress point where the thread ends. A rolled thread will always be stronger. Maybe I am oversimplifying a more complex problem, however, I believe a high tensile rolled thread stud of similar design, would solve the problem. Irrespective of what ever else is causing the problem, the catastophic failure occurs when the studs ends let go. I have expressed these comments to Jabiru now on two occassions.
I note that the new engine has spacers at the base of the cylinders. I presume these are the .5mm ones designed to reduce the compression ratio. It runs well now but how will it be around the 300 hour mark??
Jabiru have ironed out a lot of other problems with their motors, but appear reluctant to tackle this one.....Best Regards, Bob