On 9/2/2019 7:10 PM, Paul Dorsey wrote:
> Gotcha! I may be dumb but  I I am dumb, but,Iâ??m no dummy, I donâ??t
> have an aluminum head on my motor. Do theymake aluminum heads for our
> motor or do they? Anyway theyâ??re out of my price range.
> Â As I was loosening the bolts that hold the head on, Â I got to
> thinking, I wonder if there is a sequence for loosening these head
> nuts . Â Metal bends, You know. Perhaps that is more critical for
> something like aluminum heads.
There have been attempts at making aluminum heads for the wet-sleeve
engines, but they've been largely unsuccessful, for one major
reason--they have been designed as analogues of the cast-iron head done
in aluminum--dimensionally and in configuration, they're duplicates of
the original. For that reason, they don't have the mechanical strength
of the cast-iron heads, and can't force down the liners as well as the
originals, and therefore tend to leak. There are a couple of people on
the lists who have installed them on their engines.
The problem is beam strength. Cast aluminum simply isn't as strong as
cast iron, so if the dimensions are identical, then the cast aluminum
head will tend to bend around the liners rather than punching them down
into the figure-eight gaskets. That produces leaks at the head gasket.Â
An aluminum head for the engine is a good idea, but not as currently
done. Future examples really should consider radical redesigns to
accommodate wet-sleeve construction, in the way of increasing beam
strength. I've done some preliminary work on just that--thicker, taller
heads in which the outer perimeter is raised and thickened, using a
flatter cast valve cover socketed into the upper surface so it occupies
the same space. And, of course, adding crossflow port configuration,
which should have been done right from the start. It also wouldn't hurt
to machine the block lower cylinder lands smooth and machine the
cylinders for o-rings, which solves the figure-8 gasket compression
sealing problem. The cylinders only need to stand proud enough (a
thousandth or so) to ensure that the cylinder head locks them to the
block so they don't travel up and down with piston motion.
Something like that would work pretty well, methinks.
Cheers.
--
Michael Porter
Roswell, NM
Never let anyone drive you crazy when you know it's within walking distance....
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