First time on here.. Easy on me.

I picked up a 1965 impala supersport project car. It is coming along well but when I get it up to 65-70 it starts to surge and not go any faster. Feels like it is not getting enough gas. The previous owner put a elderbrock carb and intake on it. I changed the pump and also replaced the sending unit from the tank as the sock was falling apart. Ignition is new from distributor to plugs. No difference. It goes up to 65 mph real good. Any ideas?

To lean?

 

Sounds like it needs a little calibration between the cruise / power modes.
This should help you out.

http://www.edelbrock.com/automotive_...ers_manual.pdf

 

Sounds like it's running way too rich and needs to be leaned out a little because it's choking.