It's a Holley 2 barrel 500CFM model number 4412-3. As far as I know everything in the carb is the same as it was brand new out of the box. Original jets, power valve, and sprayer. I don't have any other 2 barrel carbs laying around that I could throw on it, but I do have a 4 barrel intake and Rochester carb off a '72 Skylark sitting in my garage. The intake needs to be cleaned up, but I rebuilt the carb and put bushings in in shop class 5 years ago. It has very little run time on it since the rebuild.
Quick update: I rebuilt the carb, and put a new set of plug wires. Didn't make a difference. The engine has actually been running rougher and rougher every time I work on it. Now it almost seems like it's randomly misfiring. So I pulled the plugs and they're all dry fouled really bad. Could this possibly be an issue with the ignition coil? I'm currently running a cheap BWD coil. Edit: I have an Accel Super Coil 140001 sitting in my trunk, but it's missing the ballast resistor that it comes with. Is it OK to run it with just the stock resistor wire?
Any points system should have resistance in the primary. Is the resistance wire still there? Have you checked it with a voltmeter? Without the resistance wire, the points won't last long. Do the test described here, http://www.v8buick.com/index.php?th...ystem-function-tests-and-modification.248990/
So with points closed and key turned to the on position I should have 5-5.5 volts and ~9v while cranking with the distributor coil wire disconnected and grounded to the block. Any less than that would point to a bad coil?
Less than that would indicate too much resistance in the primary. If you measure 12 volts in the first test, it indicates there is no resistance in the primary. That would shorten point life. If the plugs are carbon fouled, it could indicate a weak ignition. Worn points would be one cause. A weak coil is another. If you have the proper resistance in the primary, you can use your other coil, the ballast resistor is not needed, it's redundant.
Quick update: put in a new Pertronix III coil and distributor and bypassed the stock resistor wire with a new 12v line last night, car starts and idles quite a bit smoother than before. Car is still backfiring through the carb under load, though. Seems like it's past due for a top end rebuild. Checked the timing chain for slack while I was swapping in the new distributor and there seems to be quite a bit. And watching the engine run with the valve covers off it looks like the lobes for at least the #1 cylinder are pretty worn.
