wrote:

If I'm looking at this properly a standard VW water-cooled inline
crank (or most any similar 5 main bearing inline 4 crank) can be used
in a 90 deg. "V" 4. This would give plenty of room for fins. I think
all of the water-cooled VW cranks have 86mm or longer strokes and the
matching stock rods are between 7mm and 30mm longer than air-cooled
units, which should give good low speed torque. If it were a push rod
motor parts count would not be much greater than an inline?

A stub attached to the flywheel end of the crank and ground with the
mains to match a stock Continental front bearing, IMHO, would take
care of prop loads.
======================
Leon McAtee

What about using an American V8 crank to build a straight air cooled
four? All the ones I've seen apart had 2 rods per throw and that would
space things out more. Machining down the counter weights would be
required but it would still leave you with a very strong crank. A light
weight aluminum clamp that looked like a big end of a rod could be easy
to make to block off the extra oil ports.

Another option would be to take a lesson from the so called V6 VW that
is little more than a staggered in-line six. Staggering the cylinders
to make a shallow V4 would also improve cooling. The problems of uneven
firing order could be solve by using a distributorless ignition or a
pare of 2 cylinder distributors. This way you could choose any in-line
4 crank that is both cheap and common as dirt (like the Toyota 20R for
example...)

Tony