4:56's on the street with 27-28" tires is fine in my book. Plugs are white? Depends on how many runs you have on them. May not have shown any color yet. What heat range plugs are you running and are the float levels a little low? Maybe the valve springs are weak at 7,200 rpm's. Points may be good. Motor has to be pretty cool between runs if you want to make some power. Maybe to hot down where you are. Ice, ice and more ice!
