Ok, I brought out my mini-lathe and proceeded to modify or repair the Norvel Diesel head.
You can see where I cut in about a 2mm relief to the threads at the tip to match the unthreaded part of the cylinder top.
I also machined off the conical or tapered edge they had left on the tip as well, so that it now fits the copper head gasket shims better instead of tearing the shims up like it would have done. The head now sits a little lower on the cylinder top, but that is expected. In machining the edge flat it exposes the contra piston a little more. So if that winds up being a problem where the contra piston goes down too far, In hindsight, you may need to mill a little off the top of the contra piston. On my fix the contra piston now almost touches the top of the piston, so there is little to no combustion chamber, thus the compression would be way to high. Fortunately, the inside of the contra piston is threaded, so you can screw it onto a bolt, with the head cut off and shave a little off the contra piston to get the combustion chamber clearance back again. You actally shave a little off the skirt or part of the contra piston where it threads onto the bolt.

It is interesting how when you zoom in on a part and blow up the pic real good, how much fuzz, dust and stuff there is showing up on the item.



Repaired head now sits lower on the cylinder than the


unrepaired head here shown sitting a little higher on the cylinder.