Chevrolet: Rough Idle, smog equipment, pcv valve

Question
I have a '77 Nova 305, 4bbl, all smog equipment removed. As the motor gets warmer, 10-20 minutes, the idle gets progressively rougher.  

Answer
Mike
  I would give it a good tune up and replace the plug wires if they look bad. fuel filter, timeing, and pcv valve, and adj. the carb. the 2 screws in the lower front of the carb. turn them in all the way slowly till it sounds as it will stall than back it out when it sounds as good as it can apx. 1 1/2 turns no more do one at a time after you have checked and replaced the plugs/ points/ cap/rotor etc. as in those years the engine must have all of its parts in good condition and replaced often.those motors will run forever if kept up right. ok again I would check everything and replace what is needed.