The 312 in my T Bird is prety much a copy of an engine that Ted built several years back and did an article in Y Block magazine. I've always ran the E carb setup on mine. I'm in the process of switching to the Blue Thunder intake that Ted ran and a similar 750 Holly 4 barrel. Teds jetting was 77 primary and 89 secondary. My carb came with 76 primary and 80 secondary. I think this is close enough to start with. My good friend mechanic buddy says I should go with 89's in the secondarys. Ted was getting around 427 horses out of his. Opinions?