OK, unless and until I hear different, I'll assume that the 260hp factor is the figure to use when doing class calculations for everything except a Bird in '77. And, as of now, I'll have to use the shipping weights listed on these Class Racer info sheets. But I'll ignore their weight break calculations and do my own with a calculator.
So, by using this method, it appears that the highest class that could be run with this engine in a non-Bird is with a Cat 2-door.
3601 lbs / 260hp = 13.85
So, if I understand the rules correctly you can take out weight to meet the minimum for the class your car naturally falls into. Or you can take out more weight to meet the minimum for the next higher class. Or you can add weight to make the next lower class. So, that means that most cars can run any one of 3 classes just by adding or removing weight. Is this correct ?
If so, then the 2-door Cat I mentioned will naturally fall into the 13.50 weight break class, which is L/SA. Or, I can remove weight to meet the minimum for the next higher class which has a 13.00 weight break. This will be a K/SA with an index of 12.65.
13.00 x 260hp = 3380 lbs
3601 - 3380 = 221 lbs
If my calculations are correct, you'd have to remove 221 lbs from the 3601 lb shipping weight, to fit the 13.00 lb/hp weight break perfectly. Is it legal to run that far below the shipping weight ?
Just out of curiosity, what year did NHRA start allowing you to add and take out weight to make different classes. Before they did this, did they 1st just allow you to remove weight to meet the minimum for your natural class ? Or did they make the changes all at the same time ?
When we ran Stock, the car ran at no less than its shipping weight--period. What ever class it naturally fell into, that's the class you ran with that car. That gave some cars a weight advantage. We ran a 330hp '68 Bird with a 3300 lb shipping weight. So it was a perfect fit for the 10 lb/hp weight break--E/SA.
