Holly Carb Identification

[CJD]

9.5 psi is too much pressure for even a Holley. You want to drop that to 7 psi max or the pressure will overcome the float valves. An inlet regulator is a very worthwhile investment. That way you can run decent pressure to the regulator, which knocks it down. That way you always have plenty of pressure to fill the bowls when you punch it, but not so much as to overfill the bowls.

750cfm is for a big block. Bogging is confirmation that you have too much carb for a mild 351ci. Engine.

The edelbrock is a decent carb. In most part throttle situations it is even better at metering fuel than a Holley. The only advantage of a Holley is that it is infinitely adjustable for highly modified engines. It doesn't sound like your engine is highly modified.

I guess I am trying to say (again)... You need a 600 cfm Holley with vacuum secondaries and an electric choke. Your engine would be happier going down to a tiny 450 cfm...but will always run like crap if you put over 700 on it.

You are on the right track with a levelling plate. No carb will work right if the bowls are tilted...especially a Holley in which each bowl fills 180 out, so one float is high and the other low. The edelbrock central float may have an advantage at a tilt to the Holley.