wrote in message
...
On Jan 8, 3:56 pm, Monk wrote:

A Subaru?
---------------------------------------------------------------------------------------------------

First off, we can forget about lost-foam or anything more exotic than
green-sand, simply because there aren't enough of us. So we stick to
standard, readily available valves, valve guides, valve seats and
studs. The fins make the castings pretty tricky but if it was easy
you would have seen it years ago.

So we make a L-head and an R-head; mirror images. We do the best we
can with the fins but recognize our limitations and leave the most
difficult of them as CUT fins: Rather than try to cast perfect fins in
a couple of high-risk areas, we settle for a quarter-inch bar of
aluminum that's configured for easy SAWING, which we do as part of the
flash clean-up.

-R.S.Hoover

------------------------------------------------------------------------------------

I've alway thought it would be more practical to CNC saw all the cooling
fins. Seems a bit extreme at first glance, but if you go to the time or
expense to fabricate patterns to cast the heads, we must be talk about doing
more than just a couple of sets. So the programming cost might well be worth
the cooling efficency of extremely detailed cooling fins.