I replaced my old Quadrajet with a remanufactured Quadrajet but they don't have the same exact model. The new one has an extra vacume port. I plugged it of but it runs rich. This is my second one because the first one did the same thing. I've adjusted every thing to spec for the carb but I'm still getting a ton of carbon comming out the tail pipe. I was thinking if I take it back I can get instore credit and thought I would get an Edlebrock carb instead since I just can't get the rebuilt ones to work right for emissions. For those of you that have had both carbs what type of differences, ei: gas milage, performance, etc.. did you notice. Any comments would be a big help. Also what else to you have to change? Fuel line, Air Cleaner, etc..?