Edelbrock Carb help

I have a slight problem i hope someone can help me with. I have an '81 GMC 1500 w/ a stock 305. The problem is with the Edelbrock 600 cfm #1406 carb sitting on top of that 305. I just did get the truck running the other day with a brand new set of NGK spark plugs and a new battery and now it idles perfect but when i drive the truck it has real bad low end power and then as it warms up (about 3 miles) it starts acting like it is running too lean (pedal all the way to the floor is the only way to keep it running but i aint accelerating much if at all) but it is blowing a lot of black smoke (sounds to me like it is too rich but it might be from it sitting up for the last 6 months with out being ran). I have tried and tried to adjust (idle warm and cold are two very different settings with about a full turn difference) it but it aint workin. Any one have any ideas. oh yeah by the way the guys at edelbrock say that 600 cfm is too big for a 305 but every one else says it is just right. what is the truth?

i've seen an elelbrock carbs where the float tab was bent enough that it wouldn't seat the needle valve. the very first thing to check when working on a carb is the choke. does it open all the way when the engine is warm? try adjusting the choke so it is held wide open.another carb trick is to hold the throttle linkage wide open untill the engine revs up high then hold the choke plate closed with the throttle open untill it almost dies then open the choke. this will make lots of smoke but what it does is suck lots of fuel through the jets and helps clean them out. did you change the fuel filter? if it worked fine before what i would do is get a gasket kit and take everything apart, give it a good cleaning, set the floats and start over. also make sure you don't have any vacuum leaks and make sure the timming is correct. a 600cfm should work fine on a 305.

The carb is brand new so the gaskets and the filter should be good. I was working on it today and i noticed that the vacuum like going to the charcoal canister is busted (somehow it got burned through although i have no idea how since it didnt appear to be touching anything hot) and when the engine is warm the choke sits about 5*-10* short of all the way but i am thinking that it should be good enough. Once that vacuum leak gets fixed (tommorow) i willl see how she runs and post back on here if i have anymore problems. I am also going to make sure that the timing is good. If anyone has anymore ideas for me to try while i am at it then by all means let me know because i am but a newbie to the whole edelbrock adjustment world. Oh and one more thing i took one of the spark plugs out to check to see if i was getting too much fuel and they are carbon fouled after only about an hour worth of running so something doesnt seem right there. Any ideas are welcome. thanks