Just rebuild the engine in my dad's 69' Fury convertable. He wanted a four barrel carb upgrade. So I got an old Edelbrock performer intake and milled the name off and painted it like stock. Got the engine in car with a Holley 650 vacuum secondary that came with a metering block on the rear for additional tuning. Bought carb off Ebay. Turns out everything had to be moved around to accomodate the Holley. And now the Holley proves to be junk car ran terrible. Put the original 2 barrel back on and every thing runs fine. But, really want to make the switch. Was hearing the Carter Thunder AVS was a great little street carb.

This is a 383 with a cam ground for mileage and a little bowl work behind the valves. Should I rely on the CFM calculator and buy the 500 CFM sense the car is not driven for performance or get the 650 which may give a little more performance on that occassional two lane road sling shot pass?

Leon