Love to see you do this:
That would represent the carb inlets just somewhat open but the regulator set lower. Should be easier on the carb's inlet system to control and have less turbulence and aeration.
Then you could try with the ball valve set at 4 psi, which would be the same pressure drop between the regulator and the carb as in last night's test (9 psi to 6.5 psi).
