Quote:
Originally Posted by Dave Casey
If my memory serves me correctly,1970 has different engine specs, assuming it is a 375/396/402 combo. The exhaust valve is bigger is one differance, and the earlier cars are true 396 ci and the 70 is a 402(bigger bore) .
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The 1970 is allowed a 1.88" exhaust valve, the 1968 is allowed a 1.84" exhaust valve. The dome volume and chamber volume is the same, the dome height is lower for 1970. The other difference would be the intake, if he was running the 163 intake. In 1968, the plenum divider cannot be cut, in 1970, it can. Yes, there is a 0.030" difference in bore size.
Given the car has been campaigned as a 1968 for the most part, it probably meets those rules. I don't think Clark Holroyd has been cheating up his 396 all this time, using 1970 402 specs and running it as a 1968.
My point was, you can't run a 1970 in AA/S. So if you want to run the car in AA/S, run it as a 1968, there is no disadvantage. Most are running the 401 head and the 359 intake. So the only possible advantage to the 1970 is the 0.030" bore size gain, and the 1.88" exhaust valve. Well, the cubic inch gain from a 0.030" bigger bore will be minimal, as will the unshrouding of the valves, which would be entirely negated by the 1.88" exhaust valve. Again, not seeing a real disadvantage to the 1968 combination if you want to run light and go AA/S racing. Besides, it's the only one that fits the class.