"Bertie the Bunyip" wrote

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.
--
Jim in NC