Weber IDF always rich- Please help! Options

[tornik550]

I have dual weber 40 idf's. I cannot get the mixture correct no matter of the changes that I have made. I foul the plugs with dry black soot in only minutes. The car runs fairly well. Could be fine tuned however right now I am working on gross tuning. Heres the background info-

Setup-
-1.7l case now 2.27l by changing jugs to 96mm and crank to 78.5mm
-2.0l heads (I also have stock 1.7l heads, I have had the same issue with both heads)
-A "fairly aggressive webcam camshaft setup for carbs". I do not know the exact lift and such. The previous owner increased the displacement from 1.7l to 2.0l. He changed the cam when he rebuilt the engine. When I rebuilt the engine, I used the same cam. I had this rich mixture issue before and after my rebuild.

Carb info-
-Dual weber 40 idf's freshly rebuilt with new needles and seats
-main jets 120
-air correction jets 200
-tubes- f11
-idle jets 50
-vents 32mm
-floats set at 10mm (rich mixture), 11mm (rich mixture), 12mm (rich mixture)
-fuel pressure at 3.5

Other Info about my engine-
-MSD 6al ignition
-MSD Blaster 2 Coil
-Bosch 050 distributor with pertronix
-Autolite 63 spark plugs gapped at .030

I have tried a few things however I have not been able to change the problem. I only have a set of larger mains which obviously didn't help the issue. I have checked to make sure the needle is seating properly. I have removed the air correction jets to see what would happen- no major change in the mixture. I have a set of 34mm vents on the way however I doubt that will change much. It seems to me that with the carb setup that I currently have, I shouldn't be fouling the plugs after running the engine for only a minute.

Any ideas would be greatly appreciated.

(Yes, I did post something similar on 914Club. I am trying to look for as many ideas as I can find).

[tornik550]

I just got back inside from examining my butterflies. I believe that I have a combo of issues. It appears that 3 of the 4 butterflies were very slightly misaligned. I was able to realign all of them and they seem to close and cover all progression holes. Now I am having another issue however I am pretty sure I know what the problem is this time.

After re-aligning the butterflies, I set the idle mixture screws at 1/2 turn and the idle speed screws at 1/2 turn after light contact with the lever- wouldn't start. I tried different scenarios of backing out the idle mixture screws and turning the idle speed screws in. Basically once I advanced the idle speed screws to about 1 3/4 - 2 turns, the car would start without difficulty however I was shooting black smoke out. I turned the idle mixture screws in all the way and the engine would not run (unless I turned up the idle speed screws- opening up the progression ports). I opened the idle mixture screws about 1/10 of a turn and the car ran great, no smoke.

SO am I correct in assuming that this means that my idle jets are to big? If so, I am in luck because I have smaller jets on order. Also, does turning the idle speed screws to about 1 3/4 - 2 turns sound reasonable (I get an idle of about 1000 with this)?

I am absolutely amazed with the wonderful help that has been provided here.
THank you!!! (IMG:style_emoticons/default/beerchug.gif)