Strange running behavior/erratic timing

[bhobbs]

Hey all. Since the last time I posted, I managed to solve my alternator bracket problem on my '68 327. Turns out Autozone has an entire aisle of things that fit. I ran across a hot rod show in Granbury, TX on the 4th of July, and saw everyone with a 327 that had a single wire alternator was using the same generic chrome bracket from Autozone. Who knew.

So now, with new water pump and radiator installed, new plugs, new wires, and a new coil, it starts reliably, and will run like a banshee so long as you're giving it gas. If you leave it at a specific rpm, it just bogs, and stumbles, usually backfiring and blowing flames out both ends(intake and exhaust). At idle, it just stumbles and dies. I've not rebuilt the carbs(reman. 4bbl of indeterminate lineage, but pretty standard-looking), but as it is(no adjustments at all), it used to run and idle, if poorly due to the previously poor spark. Dwell is a consistent 32degrees at all rpms, so a little long, but again, it was running well at this setting prior to the rewiring, new Hooker headers(which are still open, I haven't put the exhaust on since I'm still having fun annoying the neighbors), new plugs/wires, and new coil. The previous headers had blown the seals at the down pipe, so they were effectively open.

Checking the timing, it's all over the map. From a little retarded to way advanced. I replaced the hose from the distributor to the carb, and have tried crimping it off to get the thing to calm down, but it seems insistent on not running smoothly. I also put the original air filter assembly back on, and hooked up all the hoses. Just seemed to muffle the noise from the carb was about it. Behavior all around is the same.

Spraying carb cleaner around the manifold didn't seem to make a difference in how it ran either. Any ideas?

Thanks,
Barry
'68 GMC Custom LWB, 327