I have 2 drag cars,1-500 ci /400,1-440,both big roller ,both has originals,both in lite weight darts,cant get them to run no faster than,6.20s in 1/8.i had a 440 that had b-1 mc heads,it ran 5.70s,my indy 440-1 and indy sr heads ran better,plus weight less,b-1 are very heavy heads
I hate to say this but if you had a big block mopar with B1 heads on it in a lite weight Dart and it only ran 6.20's I wouldn't tell anyone. I would put that info in the vault and lock it up. LOL. My buddy's Duster runs 5.80's with Edelbrock heads.
