The power valve number is not a size or diameter, and has no effect on how much fuel is added when the valve is open.
It's the opening vacuum point: a "65" (6.5) is closed at vacuum levels above 6.5 Hg", and open at all levels below it. When you put your foot down slowly, a 85 opens earlier than a 65, etc. The problem is that if you guess wrong, it's open all the time and there goes your gas mileage. Using too low a number means no extra fuel is added until later in the throttle position. With a really small carburetor and low PV number it will never open.
How much fuel is added is determined by the power valve channel restriction located in the body casting. It's a drilled hole, not a jet or an adjustment.
