Originally Posted by inquiring_mind2
I have a 427 bored .60 over. I have 12-1 compression I am running torco 110 octane. I am using and ngk ur 4 plug. I put new ones in made one pass and 135 246are black 7 8 or a brown color. What is causing this. I am not the best with carbs but if you explain it to me I can figure it out. I think I am running it to rich. But I am not for sure how to adjust it. The carb I am using is a 4500 series dominator 1050. With an victor jr 454 in take. Any help would be greatly appreciated. I am also runing the timming at 38 degrees
To judge how to rejet the carb you need to determine which jets are causing the blackened/rich condition. If you made a pass, came down the return road, grabbed your ticket and putted back to your pit the primaries could be the culprit. If you chopped the throttle and shutoff right after the pass and pulled plugs then it would be fairly safe to assume the secondaries are contributing to the problem. Also make sure it's not an oil related issue. Oil into the combustion chamber can cause a black plug as well. It would concern me that 7/8 are that much different in color, although cylinder to cylinder variations are common. Make sure there is no oily contamination in the intake plenum. You would feel it. Shine a light down the ports as well and look at the valve stems and guides.