It's about a 70/30 split. 70% of the time it runs very smooth. Then randomly I have an idle drop and runs rough. After awhile it goes away. It may run good the entire drive. Then happen the next time. Been this way for years. Was wondering if it could be a sticking valve or maybe faulty lifter? The ignition system is all new minus the coil and distributor.
What are you running for a carb? Maybe a possible vacuum leak, check the throttle shaft for play. Especially on Quadrajets, the shaft bushings can wear out and they'll run just dandy and then start sucking air and lean out. When it runs rough, start spraying either WD-40 or Brake Cleaner if your engine isn't detailed around the base of the carb, intake ports, throttle shaft, vacuum booster, etc. Anywhere that has vacuum going to it. If the idle changes, you've found a leak.
Hey thanks, I knew that trick at one time. It's a two barrel Stromberg. I'll give it a shot. I did change the carb about ten years ago. I still have the old one.
It sounds like an intermittent vacuum leak to me, too. I have a qjet with a slight warp to the surface between the body and bottom; it would act like that. Using a better gasket seems to have fixed it. Patrick
