Originally Posted by JEFF69Z28
NGK 7
Ding, Ding, Ding.... We have a winner. On race gas in a drag SBC with your combo run 7's. I only run 8's in my 15.5 to 1 SB2 head small block. The only two reasons to run a colder plug would be in a forced induction setup, blower turbo or NOS, or maybe a step colder with methanol. Maybe.
If you have E85 in the area a much better overall choice for fuel, you will need to make sure the fuel system is capable of passing enough fuel and a carb properly modified.