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 had two o-rings so I put them on the idle jet holders on one carb. I also check the air ducts and I can see the idle jet through so they are open.

I believe that my problem is primarily with the idle circuit.

Turning the idle mixture screws do not seem to make any difference at all. I have them all the way in and I still have the rich issue.

I rechecked to make sure that my float needle and seat were seating ok. I tried to shot low pressure air into the fuel input with the needle closed. I could not hear any leaking air.

I also checked the compression on 3 of the 4 cylinders. All were around 140 when the engine was half warm. I got a phone call so I didn't check the last cylinder until the engine was cool- it was 110 but I am not sure the compression tester hose was on all the way. I do not think that the 110 cylinder (#1) has anything to do with my problem cause I have the rich issue with all cylinders.

I should also mention that I am running a CB performance fuel pump. I was running a fuel pressure regulator however I recently found that it wasn't working properly (it would surge). I have removed it so I do not have a fuel pressure regulator or gauge hooked up now. I had this rich problem before and after having the fuel pressure regulator on however I do not know if the regulator was working properly. I have a new regulator and gauge on order.

I agree that something is clearly very wrong and I doubt that it is a jetting issue since I am already using small jets. I just cannot figure out where the fuel is coming from.