On Jan 8, 3:56*pm, Monk wrote:

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

Not bad. But it's going to come down to the Bottom Line. And in
that regard, the individual heads are the winners. Why? Because we
can do the machining ourselves.

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.

There's a couple of directions we can't go but if we borrow a page
from the Corvair we can position our exhaust stack just about anywhere
and still have a good seal. Most of us have MIG, which means we can
do the stack-extensions. And since it's a new casting we can provide
the boss for the hold-down bolt.

Here again, borrow a page from the Corvair (or from GM) and we end up
with a 'rocker arm' that actually works. The tricky bit is that it
does NOT need to be aligned on a shaft... we can literally put a valve
anywhere there is room. And that means at any angle as well.

Domed or hemi-shaped chamber won't buy us anything. I'm pretty sure
of that, based on some work I did in that area about 30 years ago.
But that's actually to our advantage. By keeping the combustion
chamber simple we keep our valve-train geometry simple. AND YES, we
run juicers.

Exhaust outlet to the stack is probably a rectangle, as with the
Porsche. We put the wiggles into the exhaust stacks, which we make
out of Monel or whatever, secured with that bolt we stole from the
Corvair.

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