This is not a definitive answer re the question, how many head castings
could there be? , but as far back as 1996 when I was standing in front
of Denis Welch and his display cabinet of alloy heads I asked was it
from the same source ( foundry ) as the Southern Carburetor Co. unit.
He very quickly replied NO. His heads were cast without a combustion
chamber and Denis then had the flexibility to purpose machine the head
to suit the end user's spec.
This was a long time ago but at that time the market was smaller than
today but there was more than one supplier.
Some of the big issues with castings are as Larry has highlighted plus
the placement and stability of cores and the quality and preparation of
sand / chemical sacrificial items used in the process.
I was once involved with a major foundry in Australia where with a brand
new, improved furane sand molding process had been commissioned and it
had a lot of porosity issues. All of the 'old hands' failed to
recognises the cause of the defects. I was just the simple young
engineer, without foundry experience, asking the stupid questions that
eventually led to the causes in casting porosity.
Back to the Denis Welch system of casting without a combustion chamber,
a side effect would have been one less core to shift causing wall
thickness inconsistencies etc.
'More than one way to kill a cat'
Joe with a 47 year old original ( ex WWII melted down Spitfire ! ? )
aluminium 'works' head ( 6 cyl )
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