Thanks guys. I've spent years putting this car together and don't wanna crunch it.
Fast68, I'm actually in the process of selecting my tires to. I have 15x10 wheels in the back of my mini tubbed 71 charger. It's auto, 9.5 4200 converter, Dana 60 4.10, has the multi clutch posi (forget the real name of this type of diff), 446 with the st21 cam, 950hp holley, 1 7/8 long tubes into dual 3", makes 525ish hp (little more tuning to do), about 4000lbs with me, I'm gonna use drag radials but can't decide on what size, what do you think?
Your combination sounds to me like it should be in the mid to high 11s, once it's sorted out. That'a lot of weight, and it doesn't sound like the suspension setup is especially drag-focused, specifically those big torsion bars won't help with getting the front end up off the line to help plant the tires.
I don't think a 275/60 is tall enough. The ST-21 is not a high RPM cam, which is why I think it needs something in the 29"+ diameter to keep the revs down with the 4.10s on the top end (assuming 1/4 mile, not 1/8).
If the suspension & steering aren't sloppy, it should drive fine on radials.
