What Jack Drews posted looks about right. I would post a photo but don't
have a digital camera yet. The pins I have used are 10/24 machine screws and
the end of the screws sit against the outside bottom wall of the exhaust
port. The first head I saw reinforced this was was off of Carl Swanson's
Morgan. I bought the head from him in 1966. I think that the pining was
actually done by Kas, or at least in the Comp dept shop. The weakest are is
that next to the triangular water hole at the rear of the head. I t is
possible to look into the water jacket and see that the casting tapers
gradually thicker as it goes farthur from the actual water paasage hole, but
is still quite thin and bridges a wide area with no internal support as you
follow the line of contact with the cylinder liner. The pressure of the
cylinder liner, .003" to .006" proud of the block, and the heat and
vibration stress while the engine is running tend to cause the head surface
in this area to warp up and away from the liner if this area gets to thin.
The pins spread the load to the exhaust port bottom floor and prevent this
"collapse."
There are normall 3 pins in this area, about 3/8 " apart. These are
dupicated in each of the cyinders. Then the is 1 pin in the "mirror image"
location of liner contact, still on the manifold side of the head. The head
is plenty strong on the spark plug side. The only problem over there is the
"creep " of the spark plug cooling water passageway toward the combustion
tchamber and head gasket sealing area as the head is milled more and more.
Regards,
Greg Solow
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