i am experiencing surging at 50 -60 mph, i must inform you i have a fairly steep cam and do experience surging at slow speeds in and around town with the 427 L71 and 3;70 gears and suspect this is normal . I have had the carbs professionally built by J, Luck and i am running a 44 plug , the plugs are showing a white electode and the ceramic is a clean and marks of soot, am i to read these plugs as too high a heat range or am i lean. temp is reading under 200 and seems fine and i run a lot of initial timing with no pinging . I dont want to open up the centre carb because J.L did build them and thought i would ask the pros for opinions on these remarks above.