RE: black widow running time
samp615,
Assuming that you do have a Black Widow, inside the tank is a piece of tubing that can be adjusted to various heights for the type of flying you are doing. If the tubing is set high, you get the same type run whether you are flying upright or inverted. When you are flying, the fuel is thrown to the side of the tank so the tubing will pick it up. If you are holding the planelevel, you will run only half the fuel out before it stops. Hold your plane with the outboard wing down and it should run longer.
Good luck with it.
George
Edit: Oops, I was assuming a control line setup. If you have it in an RC plane, you need to remove the tank and adjust the tubing to the bottom of the tank. Be careful to not lose or pinch the small "O" ring between the tank and the backplate.