Yes, some air cooled engines have tapered bores (when cold) to allow
for different rates of expansion in cylinder base-to-head so that
it's perfectly cylindrical when up to temp, but i don't know of any
aircraft engines that have that feature.

Really? I thought that they did have a tighter bore at the top. I
guess I read wrong, or remember wrong.

Maybe. I didn't know that they did. It would make sense if they did, all
right. I don't do machining. I just run my fingers over the pretty parts
when they come out of the machine shop!

This ought to be an easy question for someone in the group. Surely, there
is someone that does do machining on engines that hangs out here, that would
know for sure.

Anyone?
--
Jim in NC