Hi All,
I answered my own question last night. I have 3 heads at home, my original
stock '74, and two Circle B's dating from '70 and '73.
Comparing the '70 with the later heads, the ports differ only in the intake
locations, as the exhaust ports on all three heads are in the same
locations. The intake ports on the '70 are 0.280" closer together in the
early head compared with the later heads, as stated by Bob Lang.
What confused me is that the '73 head that I have came with big valves that
were standard on the early narrow port heads. It seems that the previous
owner had opened them up.
I looked at the price of forged s/steel valves last night. OW! I'm real
thankful I'm not rebuilding a 4-valve V12.
Shane Ingate in Maryland
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