How to calibrate the fuel flow indication in the 3500?

[johnb]

In my low-wing 4500 installation (red cube, EFI) I dialled in the FF a little bit differently. I plumbed a temporary Tee into the pressurized return line and fitted a needle valve. Turned on the pump and adjusted the needle valve to bleed 21.3 oz/min (10 gal/hr). Then adjusted K factor until gauge read 10 gph. Eliminates the variable of "full" tank when determining actual fuel burn. If the tank is a wing tank with a large surface area, minor differences in fuel fill levels over a large area can result in significant fuel volume deltas.

YMMV
John

[Rob Hickman]

If the tank is a wing tank with a large surface area, minor differences in fuel fill levels over a large area can result in significant fuel volume deltas.

YMMV
John

So how do you know how much fuel you have in the plane? I seriously doubt that it is a significant amount if you fill both wings to the top of the filler.

When you adjust the needle valve to 10 GPH what are you using to measure it?