Quote:
Originally Posted by BBF67
Correct starting in 1967 with no penalty. Prior to that the GM or 401 aluminum head gets the horsepower penalty.
Where does the class guide show the 396 Corvette with a natural class of SS/C?
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According to the class guide, the P/W factor is 7.65. That is SS/D.
The confusion may have started because of the two different methods to determine class when replacement heads are given a different power rating.
Method 1: If you say that the calculation is based on shipping weight, then the classification for the aluminum head is calculated by the different power rating divided into the shipping weight and results in a new P/W factor not listed in the Class Guide. (65 Corvette 396 shipping weight is 3022 lb / 411 = 7.35 or SS/C. The car can run in SS/B, C or D. This may be how Jimmy is getting the car classified in SS/B.)
Method 2: If you say the calculation is based on the P/W factor listed in the Class Guide, then the classifications stay the same as indicated in the Class Guide, but the weight changes. (65 Corvette 396 P/W factor is 7.65 SS/D so it runs SS/C, D or E. The minimum weights for the classes is based on the power factor with aluminum heads aluminum heads.).
I have had this ongoing conversation with people from NHRA tech for
several years and the opinion/answer changes. The last statement from them was number 2.