startin it up was no real issue, but its running pretty rough. changed the plugs, the spark plug leads, the points, condenser, rotor, dist cap, and its better but still noticeable missfire even at idle. what do i do next or is it carb rebuild for sure. suggestions anyone?
Cylinder balance test, followed-up with cranking compression test and cylinder leakdown testing depending on what you find. Figure out which cylinders are affected, which then gives you clues as to what is wrong.
Time to soak and rebuild the Carb. Be sure to get a kit with a good acceleration pump as I think even the so called better Blue types have been known to fail quickly.
Check vacuum hose leak. Pull plug wires off one at a time and you will know witch one or two are weak cylinders.
That's one way to do it. Really hard on the coil and all the insulation of the secondary ignition system, though. Better would be to use a test light. Ground the wire, put some dielectric grease on the pointy probe. SLIDE the probe between the wire and the distributor boot until the spark grounds through the bulb filament (the light does not flash when this happens.) No sky-high voltage, no stress on the insulation, and when you're done, you haven't poked any holes in the plug wires.
further to this resurrection... points condenser rotor and cap changed, plugs and wires are new, carb is now rebuilt and filter is new. same issue. rough idle, hesitation on initial acceleration, and still backfires through the carb under load. next on the list? what is the most likely issue. original block, 70,000 miles
1. Doesn't matter what's "new", what matters is whether or not it's functioning properly. Lots of brand-new defective junk available now. 2. What happened with the various tests that were suggested? I don't see that you've done any diagnosis, not even the stuff we recommended. 3. "Hesitation on initial acceleration, backfires through carb" both suggest a lean condition. What is the fuel pressure? Does the accelerator pump WORK?
Doesn't really matter for diagnosis, but was it parked 10 years ago in excellent running condition or was it parked because it was having drivability issues? Sounds like a timing issue to me, check operation of vacuum advance. Put a timing light on it and see what's happening at idle and when you accelerate.
I created a major headache once by hastily cranking a 70 350 that had sat for yrs. It had 2 or 3 stuck valves that resulted in bent pushrods and ruined lifters. Of course the heads came off too. The car was stored indoors and looked great otherwise. That was a kick in the ass.