No Hoper
Without the screw thread the head would depart on the first runup
It is a combination of the screw thread and interference fit that retains and locks the head to the cylinder
Do you have Data that shows this to be true? I always thought the above to be true. In fact I didn't even know there was a shrink fit involved.
Having now read Mike Busch's article (Link post 10 ) I tend to believe a cylinder manufacturer probably knows more about how they work than I do. I do know that train wheels seldom fall off and they don't have a threaded section to help hold them on.