Cyl head coolant leak update

[Jeff Taylor <jbtaylor@domain.elided>]

Some of you may remember a while back that I had just reassembled my 345,
tried to fill it with coolant and the coolant poured out the #3 exhaust port. Baffling!

Well, I found a 4bbl intake (non-EGR) thinking maybe the 2bbl intake was
cracked. It leaked with the 4bbl also. Oh well, it was a good excuse to give
my wife for getting a 4bbl intake. <grin>

So I pull the head (using up another head gasket) and just happen to look into
the exhaust crossover port on the cyl head in the bright sunlight and there is
a hole! It's about 1/8" dia. and apparently intersects a coolant passage. So I
go back to the guy I got the manifold from and get a rebuild able head.

I take the heads back to the machine shop and he is as baffled as I am. He
said he had never seen that in an IH head, and rarely on anything except
marine engines cooled by straight water. He rebuilt the new head and blasted
the manifold basically for the price of blasting the manifold alone. 

What I don't get is that the engine ran (not well, but it ran) before I pulled
it. Maybe the hole was sealed with exhaust crud until it got hot tanked?
Anyone seen anything like this?

Jeff T.
74 SII (finally running)