I run that same carb on my 71 BEE - 383 Magnum - Put the smaller AVS 6125 s up in the attic
Perfect - Carb is Awesome
I also blocked off the HIC
Made my own flat metering rod covers - Edelbrock doesn't sell them when I asked
104 Primaries
107 Secondaries
68-47 Metering Rods
Blue Edelbrock Metering Rod Springs , had to replace factory springs
The 4640 is for AC cars and I would look at the hot idle compensator for leaks (cork gasket) or block it like bee 71 said. Is your car AC? If not look for 4618 carb, they have different air adjusters. Check the rods to see if they are free moving and down when running, might not be seeing vacuum to pull down (restriction)