Probably the idle mixtures need adjustment. You didn't say what kind of carb so:
Holleys have theirs on the metering block on the sides of the carb. They look like little machine screws. Turn them in to lean the mixture and out to richen. Most of the time a Holley on a mild egine will have the idle mixture screws about 1/2-1 turn out from lightly seated.
Edelbrock/Carter carbs have theirs right on the front. They look like two big screws with springs on them. Same operation as Holley.
Motorcrafts have their screws under the float bowl and are kinda a PITA. Again they're tow screws with springs on them.
Basically you turn them in or out depending on which way the engine runs better. Only turn them only so far as you don't notice any significant difference in idle quality. You'll find that the idle speed increases and you have to lower it again occasionally. This will also necessitate going back and tweaking the idle screws again a few times until you get it to where the idle speed is right and as little as a 1/8 turn of the idle mixture screws in either direction will make the engine run a little rough. You'll get the hang of it as you'll be doing it often enough LOL!
If you didn't remove the distributor you shouldn't have any more problems than you did before the swap. If you did remove it then all yyou can do is "tune by ear", trying for a hapy compromise between power, starting, and pinging under accleration. It would be best to get it to where you can have a timing pointer as it makes life a lot easier.