There are tons of info about this all over the web and this site. Do a search and you will be reading all night. That said the 750 lower end torque the 850 high end power. I prefer the 750 but that's me.
What carb is best for a mild bbc the street avenger 870 or the 82750 holley
Wow, we must be on the same page, LOL. I just removed my 870 Holley SA from my BBC and was thinking about replacing it with the 82750. The 870 ran very good, however I couldn't dial in the choke for some reason and it never really worked properly. If I had to do it again I would not recommend the 870. I think it was a little big for my set-up. Perhaps the 770. Anyway, JMHO. Right now my choices are between the 82750 and the Quick fuel HR780 vs. Here is a link to the QF carb: http://www.ebay.com/itm/QUICK-FUEL-H...sories&vxp=mtr