Ok dominik.(and whoever) I tried sending you another message in the private section, but this message was too long, it wouldn't work.
The situation; a 350 chevy with a 305 duration cam/ automatic/ stalls when in gear at idle.
The thing that is causing you the problem is the cam! The duration you have chosen is HUGE for a 350 ci. If the same cam was in a 400 small block with 11:1 compression, it would be fine.
I am guessing you have flat top pistons and probably 72 cc chamber heads which means you have 9:1 compression. This is extremely low when you take into consideration the cam duration. With a cam which has large duration, you actually lose compression because the valves stay open longer and thereby compression squeezes on the compression stroke, leaving you with even less compression/power at low rpms. In addition to this the exhaust valve stays open thereby sucking some of the spent gases back into the cylinder. This all changes when you get above 5000 rpm, for then the scavenging effect promotes more horsepower.
I know all this doesn’t remedy your current problem, I am just trying to get you to understand the dilemma you are facing. What you need in your current configuration is a large stall torque converter, and a health shot of go-go juice off the line. However, that means more money, soooooo, the immediate fix so that your engine will remain running is, giving the engine more air and not more gas at idle.
With your set-up, what you had to do is set the idle screw in further so that it would idle. The problem with that is that when you do that you are also signaling to the carb that it needs more gasoline. Solution: drill two holes, one in each of the front two butterflies of your carb, about 1/16 - 3/32 large. Or, if you have 2 p.c.v. fittings in your intake manifold, install one in the usual way and in the other hose install a valve that has a large flowing capacity. The second one is not connected to the valve cover, you need to leave it breath fresh air, and when you have the right combo, install a filter of sorts over the end of it so that you do not get dirt into it.
When this is all done, your two mixture screws will actually have an effect on the idle once again. You will have to adjust these.
I will post this message on the forums because some others might need this info at some future date.
