A 426 racer told me today that he was having problems with his sparkplug fouling. He said he tried all different settings on the carb and nothing helped much. The weather was pretty cold and he usually runs 93 octain pump gas and he thought he would try 87 and the problem went away. He also told me that it runs best on 93 in summertime. Today it was arond 55 degrees and i ran 89 and it ran great. So his idea must work.