Gary,
Due to the shape and slope of the tanks, that 1" margin doesn't lose you much fuel volume. Try filling to that level, note the numbers on the pump, then quickly fill it to the brim and see how much more it is. Do this when the other tank is partially low (2"- 4") so the cross drain will lower the level before it leaks or you fly. I'd bet it's not that far from absolutely full fuel. It's also good to totally empty the wing tanks while flying over the airport. Land and measure how much fuel you put in to get it to that desired level of fullness. Then you know how much fuel those tanks really hold, not counting unusable fuel. Ed
