You can give the propane torch a try for carbon deposits.
You will need to get the insulator nose between 932F-1472F(500C-800C)..
Problem was the insulator nose never got hot enough in the engine to burn off the carbon.
Air fed propane torches burn at 3600F(2000C)
Air fed butane torches burn at 2600F(1430C)
Louis Dudzik's GM HEI ignition module installed 2015
Motogadget m-unit blue.