The backbone of the conversion is a 235 crankshaft, with the thrust bearing flanges widened to accommodate the 216 main bearing. That is a simpler conversion that machining the block web thinner to take a 235 main bearing on the #3 position, and it's something I can do on my lathe with a carbide cuter bit and a tool post grinder. The 292 connecting rod is somewhat narrower than the 235 rod, so it gets a spacer washer pinned and silver soldered to both sides of the rod cap to center the rod in the journal. The small end gets a bushing to reduce the diameter to the size of the 235 wrist pin and make the pin full-floating with Teflon thrust plugs to keep the pin centered. The 216 block gets bored 60 over to accept standard bore aluminum 235 pistons. Now, here's the sneaky part- - - - -since the 216 block deck height is shorter than a 235, the pistons would stick out the top of the block. The crankshaft will be destroked from 3 15/16" to 3 7/8", and the tops of the pistons will be machined down just slightly go give a deck clearance of zero, even with the top of the block. The final displacement with standard bore 235 pistons will be 231 cubic inches. I just finished fitting a 250 oil pump that will almost double the flow of a 216 pump. A "216" with 40+ pounds of oil pressure at idle????? Of course it's going to get the leakproof rear main bearing seal while I'm doing the machine work. An early 235 oil pan without the 216 spray-oiler plumbing will replace the original pan, or the spray hardware could just be removed from the original pan and the oil supply port to the pan will be plugged.
I've also got a 258 cubic inch version of the 216 in the works, using NASCAR H-beam connecting rods and a lot of modification to a 235 crankshaft!
Jerry
