I was going with fuel pressure too. Maybe the old mechanical fuel pump is on its last leg and loosing fuel pressure once it gets warm and everything expands.
Also is it running a manual, vacuum, or electrical choke? It could be that you tuned the carb cold, and once the choke opens you are either rich/lean. When you set the idle was the car up to temp. Also when setting the idle did you use a vacuum gauge or just go by ear?
Back to the electrical side of things... resistance increases with heat, so if you have a loose connection to the coil, then this could be one of the issues.
I would do my best first to isolate it to either an electrical or fuel problem then go from there. Maybe possibly check the compression of the engine as well.
the condition existed exactly as it does now with the old carb, prior to a rebuild, and after the rebuild, and after the new carb. I didnt do a whole lot in the way of tuning it, idle is set with it warm.
Choke is electric. It opens all the way when warm. Idle is set by ear, it's been adjusted several times in the past and the condition still exists.
the engine is brand new, 5000 miles on it. this apparently happened even before the engine was rebuilt. The older carb we have was on there before the rebuild, and im pretty sure the dizzy and ignition setup was all there before as well.
i'll check connections to the coil, but everything looks solid, as i've replaced the coil and checked the wires.
i'd doubt its a fuel problem because the carb doesnt need much pressure at all, its not running out of gas or boiling it off (carb has a spacer). it isnt hard to start once it cools down so it seems like percolation isnt the issue.
Also marn... do you have any of that crazy emissions stuff on their?
zero emissions stuff. headers to some kinda resonators. true duals, no h or x pipe.
what gets me is that it acts like its overheating. damn thing hits 200 degrees and starts sputtering and dying, then shuts off. barely runs. if you let it sit and idle for a long time it'll climb to that temp and die out. i understand that is an issue in and of itself (electric fans could help) BUT BUT BUT
no engine should shut off and die because of being too 'hot' at 200 degrees. like i said, the radiator doesnt blow off or anything. engine just knonks out right at 200ish.
you can drive for 4 hours at 180 degrees and the car is fine, then you let it warm up to 200 at a stop light and it barely runs.
or you can fire it up, leave it idling in the sun until it warms up, and it'll do the same thing after only 20 minutes of being on.
also, for the record, i can fix anyhting on my jeep, but everything i try to do on that nova is a failure.