Paul wrote:
"Colyn: I just re-read that article, Busch states:
(The head's tensile strength is reduced to 50% of its room-temperature value at a CHT of 400F, and to about 33% at 500F.)
I don't see that supported in any literature studying the properties of steel versus temperature."
The cylinder heads are ALUMINUM and the cylinders are steel. Attached chart shows that the 1000 hour strength of 356 aluminum alloy heads south rapidly as exposure temperature exceeds 300F.
Fred