Holley Carb Jetting Help, Lousy Fuel Mileage

Well, here's the latest update. After rejetting to #66 primaries and leaning out the idle circuit, my son's car is up to about 12 mpg in mostly in-town driving. Don't think it'll get much better than that, but we just leaned out the idle a bit more today, so we'll see what's left in the adjustment and how it drives.... it's about 1 1/2 turns out on each side now.