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First, do this; with engine off, turn the carburator idle-fuel mixture screws in all the way till they stop (lightly), then back them off one and one half revolutions. That is your starting point for the idle-fuel mixture adjustment. Start engine and run till warmed up. Now fine tune idle-fuel mixture using a vacuum guage connected to manifold vacuum. Turn screws till you get highest manifold vacuum AND smoothest idle.
Also, did you adjust valve lash properly. Should use .019" feeler guage with engine hot for all valves intake and exhaust. If valves are too tight, it will run crappy. If waaay too tight, will bend push rods, too loose tappets will be too NOISY and engine will not perform well either.