scotricker

You say the carb was rebuilt.
I read in another forum that some aftermarket carter rebuilt kits contain replacement parts designed for ford.

heres a copy and paste of the passage
The issue with the aftermarket rebuilding kits is quite simple. The carburetors made for Chevrolet were made in the 1950’s and early 1960’s. Most of the YF production was for Foorrdd engines, especially the 300 CID 6 cylinder which require more fuel. MOST (not all) of the current aftermarket repair kits contain a fuel valve designed for the Foorrdd engine which has an orifice of 0.101 inches. The fuel valve as used in ALL of the YF carbs for Chevrolet had an orifice size of 0.081 inches. If you do the math, the valve for the Foorrdd has an orifice size which is seventy percent larger! Using this valve in the Chevrolet carburetor will cause at best an over rich condition at idle, and at worst flooding and fuel leakage.

Just something else to look at

Good Luck