Okay, my tuning manual says to set the rear vacuum diaphragm using an outside vacuum source. What or how do I accomplish this? I am trying to dial in my 79 rochester M4MC 4bbl carb. It has a non electric automatic choke which is giving me fits right now. It fires up good but starts to stumble bad after a few seconds. After about a minute or two it will "correct" itself and run fine. I seem to be getting bad fuel economy as well. Any ideas?
