Stock or Super Stock

[Bill Harris]

Interesting combination. Assuming that is the 390 rated at 300HP it has an NHRA factored HP of 280 for stock and 300 for S/S. If it happens to be a 390/330HP then the NHRA factor is 330 for both stock and S/S. From the blueprint specs the only difference between the two is the camshaft which is a 0.408" lift on the 300HP and 0.465" on the 330HP. Otherwise they look identical, same compression (11.0:1) and same carb (a 1.12 venturi Autolite 4100).

The carb is going to be the biggest limitation. It is only about 535 CFM on a good day, and you have to use it in both stock and S/S.

The shipping weight on the 500 XL is 3924 lbs with an automatic. It's natural stock class is M/SA with the 300/280 factored engine so you could run L/SA, M/SA or N/SA by adding or subtracting weight. If it's the 330/330 it is a natural H/SA so you could run G/SA, H/SA or I/SA.

It would make no sense to run it as a 390/330 in super stock since you can use any cam you want so you would claim it as a 390/300 regardless of what it was originally. You would run in SS/KA, SS/LA or SS/MA by juggling the weight.

All of that changes a little if you were to use the Edelbrock aluminum heads which are approved for that engine. They carry an 8HP adder in stock and 5HP adder in S/S. From what I know about FEs, your better off with the OEM iron heads in most cases, especially in stock.

If you ran in H/SA with the 390/330 engine you would need to get the minimum weight 3865 lbs down the track in around 11.50 to stand a chance in a heads-up race. The index for H/SA is 12.45 so you have to at least go that quick. There are a lot of quick cars in G/H/I stock.

These days stockers are a long way from stock. You can't back-half the car but there are still a LOT of things you can do to the suspension, front and rear. Engines and transmissions have a lot of trick stuff (i.e. expensive). If you do S/S you can backhalf and put in a ladder bar or four-link and run up to 14.5" tires and everything is even more expensive..

Now, if I were you and had a crapload of money, I'd stick a 425HP 427 with two four BBL carbs in that thing along with a Jerico and run it in B or C stock. If you need to run an automatic you could do a 410HP 406 with three two-barrels and run C/SA or D/SA. Paint it to look like Barney Fife's police car and you would have a real show-stopper!