The 1946 model 216 I just disassembled does- - - - -I'm wondering if it would be possible to drill and tap those heads for 14MM plugs? The 10MM variety are scarce, expensive, and prone to cross-threading. It should be pretty simple to set up my valve seat and guide machine with the air-float work table to do an accurate job of opening up the plug holes to the bigger threads, as long as I don't hit the water jacket in the process of enlarging the holes.
Jerry
