Shotgunning parts at a problem without adequate diagnosis just increases the chances for creating more difficulties, without solving the original problem. Unfortunately, the type of structured maintenance protocols that aircraft systems have do not exist in the automotive world. Back when I spent some time doing USAF electronic maintenance, once the degree of difficulty on anything aircraft-related got beyond swapping minor components and twisting safety wire, everything went back to a maintenance depot or the factory for repair. Very little actual diagnosis or rebuilding got done- - - -we were just parts changers. I doubt that things have changed much since I went back to fixing cars 40-something years ago.
Your sooty spark plugs are a symptom of a flooding carburetor. Dump the Weber off a bridge with a deep river underneath, and go back to the right carburetor. I'm partial to Carter, but a few people still use a Rochester for something other than a paperweight.
Edit: Ed Pruss is in your area. Once you make 2 or 3 more posts and have access to the private message system, drop Ed a PM- - - -he can probably solve your problem in a matter of minutes.
Jerry
