Spark Plug Carbon Fouling Options

[tornik550]

I was hoping tha tyou guys could help me with a little problem. When I first purchased my 73- 914 a few years ago, I took out the spark plugs and they looked great. I started driving it myself and now I always have a huge amount of blakc carbon deposits even after only a few minutes of driving. I realize that black deposits normally suggest too rich of mixture however I have not made any changes to the carbs so I cannot figure why this would happen. The only thing that I changed was fuel. I also used 93 octane fuel, not sure what PO used. After this has happened, I have played with the mixture setting on the carbs however I wasn't able to fix the problem.

Could this be from a higher octane fuel? Timing problem? Too cool of plugs?

Engine info-
1.8l case however 2.4l due to new cylinders/pistons...
2.0l heads
msd 6al ignition
bosch 050 dist with pertronix
timing set at 27 degrees at 3000rpms
plugs-autolite with 63 temp, also tried 64 temp, also tried bosch plugs but I dont remember the number
93 octane fuel
plug gap .045 (due to msd ignition)

I clearly do not have a good understanding of plug reading. I have read quite a bit however I cannot figure out an answer to my specific problem. Any ideas would be greatly appreciated.

Thanks,
Steve

dual weber 40idfs