Correction. The problem is not that the CarterBrocks need tuned. It's how difficult they are to tune. And how difficult they are to find parts for and information on how to tune them. The OP talked to the manufacturer straight on and they blamed someone else for their problem. Either they didn't know they had a problem or knew it and hid the info. Which one is worse?
Here it is 2021, this platform carb has been around over half a century and the fix for a common problem that people have been dealing with for decades is still news to many. That is the problem.
That is a better statement of the problem. Let's remember Carter went out of business. Then the spin offs. Holley won the competition war especially when it came to racing. But I would not classify them as easy to work on either.
Those Edelbrocks are generic AFB and AVS. I have seen them used out of the box and work fine for a basic street car with some minor tuning. Some times I question if they even have engineers testing anymore, or just have the overseas manufacture copy an old design. I do not think many appreciate all the different variations OEM carter had with top size and shape, venturi dimensions, let alone jetting. Same goes for the spin off fuel pumps. Even washer sizes were engineered inside a fuel pump with plenty of patents on the design. All that gets washed away by an overseas manufacture that doesn't know why it was like that but can save some pennies per unit using something more generic.
I would say this for an old carb. You need to take it apart and clean and dimension the idle and fuel jets. Aluminum corrosion, growth, dirt, all tend to shrink the hole sizes. Clean it out really well, and get back to OEM base line. Carter manual or Service Manual give spec for air and fuel bleeds/jet. Have that base line then change for your motor/todays fuel.
