<VV> Engine building - bearing clearance

[John Kepler]

Happens often with inline or V engine blocks all the time, not so 
much with aluminum boxer crankcases like a 'Vair or other boxer 
unless the engine is a bit of an exotic (Porsche Ferrari etc) that 
commands some economic respect.

I've done it with Porsches and have actively contemplated it with a
performance Corvair engine....but it requires a bit more than just hogging
out the journals!  To achieve the increased precision and avoid the
collateral "nastiness" of misaligning bolt-holes, you have to metal-spray
the existing journals and then re-machine.  It adds more expense, but end up
with a better-than-stock bottom-end.  Whether it's worth that additional
expense is in the eye of the owner...I think it is in a certain context, and
it is certainly the only real way to resurrect worn cam-journals.  Finding
shops that do reasonable priced metal-spraying isn't nearly as difficult as
it used to be, and so is something to consider.  If you're going to do the
cam-journals, you may as well do the mains and then align-bore them as well.

John