Re: PSMCDR...new "tech"
Tom,
That seems to be the best solution to the teardown issue. I hope that Dan and Bob see it that way as well.
bbdon,
The 3904392 (1967) and 3919842 (1968-69) closed chamber aluminum heads did indeed use a 1.84 inch diameter exhaust valve and were the only big block Chevrolet heads ever to use this valve size. I don't know why Colvin chose to use 1.72 in his book, but it isn't correct. The 3946074 head used on the ZL-1 and second design L-88 engines in 1969 were the first to use the 1.88 exhaust valve.
There may have been an even earlier aluminum head used VERY early in the 1967 model year, casting number 3904387, but I have yet to gather any details on this head. Anyone have any information on this particular casting?
Regards,
Stan
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