307 with a newly rebuilt 2 bbl, won't idle below 1,100 RPM. Timing, points checked ok, new plugs and wires, carb float set to rebuild kit specs. Any ideas on a likely cause?

Dave

Are the throttle plates closing all the way when you back off the curb idle screw? Sometimes they need to be seated in. This is done by tapping the throttle shaft to the left and to the right a little to line up the plates with the bores. Another possibility is that there is a vacuum leak.

Thanks sounds like good ideas. By the way, I just noticed that the alternator light is staying on, even off idle. Could this be it? Maybe it does not generate enough voltage below 1,100 to keep the engine running?

Be on the lookout for vacuum leaks also. Like forgetting to install your PCV. That'll give you a wild idle all by itself.

The alternator light is a seperate problem. Highly unlikely to have anything at all to do with idle. If you have a fully charged battery your engine would run for a loooooong time at idle with no charging going on.

Thanks for all the good ideas. It seems like it is either a vacuum leak or something related to the idle mixture. Everything runs great until the engine warms up and it comes off choke and then it dies. If I hold the choke partly closed, it continues run well. However, I have tried adjusting the idle mixture from 0 to 5 full turns and nothing improves.

I have also sprayed starting ether around the base of the manifold and at each of the manifold connections with no effect.

When you have adjusted the mixture screws, are yiou making a 1/2 turn adjustment, then trying to lower the idle speed? It almost sounds like you have the butterflys open so much that the main slot is uncovered too much.
Try turning the screws in all the way, then back em out 1.5 turns. Then set idle speed.
Could very well be a vacuum leak causing you to have to adjust the carb this way.

Ironically I have just been through similar issues with both the carb and the alternator on my son's 307. I suggest adjusting the choke. Assuming you have a stock Rochester 2G, here are the instructions: http://www.tocmp.com/manuals/Carbs/Rochester/2-Jet/Manual/MCarbRoch1973__2G.htm

BTW, if you do have the 2G can you tell me what float settings you used? I'm trying to find them myself.

WRT the alternator, here is the post that helped me track down my problem (faulty connector):

http://www.chevelles.com/cgi-bin/forum/ultimatebb.cgi/topic/22/4374.html?