14 CFR 23.955 fuel flow test procedure. 150% of the engine's max fuel requirements. Per William Wynne's calculations (https://flycorvair.net/2017/01/12/critical-understanding-9-percent-of-power-and-fuel-flow/) the 3L corvair I have requires as high as 12.3 Gallons/hour at 100% power. So 150% of this is 18.5 GPH. Max climb angle for the Rebel is about 14 deg, then add 5 deg for a total of 19 deg. Aircraft was tied down with the tail wheel on the incline (as shown) and wing AOA was noted at 19 deg with a propeller protractor.
Fuel line to the carburator was disconnected and secured at the same vertical position relative to the carb inlet. 2.5 gal was placed in each wing tank. A quantity of fuel was passed through the system to ensure clearance of any air. Clear plastic bottle was marked with two 0.5 Gal increments. Stop watch was started when fuel level reached the first start mark and stopped when it reached the first 1/2 G marker.
Left tank only: 1/2 G in 1min 18 sec = 23.1 GPH Right tank only: 1/2 G in 1min 20 sec = 22.5 GPH Both tanks: 1/2 G in 1 min 10 sec = 25.7 GPH
All Fuel flow measurements exceeded minimum requirements for this gravity-fed system.