Adam:
I have a ’66 Super III. I was wondering where I should set my fuel selector when I get topped off. The last few times, I’ve noticed that the right tank is not quite full, and the left tank is over-flowing. I haven’t been paying attention to the selector position, except this last time, it was on the left tank. Is this common? Is it caused by my selector? Should I put it on the right tank when I fill up? I’m on flat ground when topped off.
Fuel selector position does not matter on these planes during fueling, as there is no tank interconnect anywhere. The only desired fuel selector position is to set it to the tank that is overflowing, if that happens, so that you use up the excess there first (to avoid losing too much out of the vents).
Most times of the year (depending on where you are and where the fuel is stored), the fuel in the ground will be colder than the average afternoon air temp. That means it will expand in the tanks later in the day, if the plane isn’t being used. The best bet is to refuel to within a quarter-inch or half-inch of the cap neck, to leave some expansion space, if you won’t need max range on your next flight. If you primarily fly locally, just fuel it slightly above the top of the slots in the tabs. That gives you at least 20 gallons per side, and keeps you from hauling around an extra 120 pounds all the time. In turn, this gives you better performance.