Carb troubles

I'v got 2 Carter RBS carbs for my AMC 196. 1 is an NOS Carter " Zip Fit " that I bought off Ebay and stuck on while waiting for my original carb to be rebuilt/ restored. When I had the Zip fit carb on the car it ran ok, and even tho it had only 5 cylinders firing, it had enough power to move itself w/o issue... when I put the correct carb ( now rebuilt ) back on ( has funky linkage for the tranny kick down, which, the cable is broke so it's really a non issue anyway ) and got the dead cylinder to fire, the car ran smooth but with no bottom end, below 2,500 or so, the engine would blow black smoke out the tail pipe and flood itself out, basicly figuring the Rebuilt carb was not the issue, we tested the ignition system when that tested ok, we changed carbs and the Carter Zip fit carb ran the car with power throuout the RPM range so somthing is screwey with the rebuilt original.. the carb is warranted for a yr.. the real question I have is if the guy did anything to the carb as it had the same issue when I sent it to him, it's why I sent it out.. when my mom called to make sure he was getting it done and if he didn't have it started to just send it back. ( 1 month he had it ) the carb was mysteriously apart and he was getting ready to rebuild it and said it would be at our door on monday ( this was on a friday ).. The carb looks rebuilt on the outside, but if I open it up to proove it's not and it is, then I void the warranty... what should I do about this?

since it is under warranty i would give him a call and tell him that you are still having the same problem. Let him offer a suggestion. Either that or send it somewhere else and get it looked at once again. Why cant you just stick with the one that works?

Sounds to me that it wasn't rebuilt right, I'd take it back.

I got the Carter Zip fit because the rebuilder was taking so long with the original to rebuild it, it was $60 buy it now on ebay so I snagged it up.. but it's actully for a manual transmission car, the A/T carb has some weird linkage for the kick down. my kick down cable is broke so right now, it's hooked up and working fine w/o issue but if I ever wanted to replace the kickdown, I need the original carb.. I wouldn't even worry about the original carb if it was a small cost but it cost almost $300 with shipping to get it rebuilt. I'm gonna give him a call to see what he wants me to do.