I am going to throw out a general observation I have seen over the years. If you are running one carb. 5 and 6 and 1 and 2 will burn lean. No#3 and 4 will run rich. A two carb. set up will help relieve the problem and a carb. on each port will do the best. A manifold with equal length runners are suppose to take care of the problem. Don't really know. OK now everyone can start throwing the rocks. lol. Hud