I got to play with the bench some yesterday. The 1.78 orifice is inside and a 1.78 orifice as a test piece test pressure was 250mm WC,
so the incline was set at 500mm vertical rise. The incline went about a inch and a half past 100% , flipped the internal plate and it went about 2.5" inches past a 100% so I flipped it back over . So do i adjust the incline higher ? Or maybe I should build a baffle on the inside , could be a air column hitting the internal orifice I dont know, give it a try and see I guess