the afb is the same thing as the eldelbrock performer it doesnt use a powervalve that im aware of....it uses a step up spring that will force the fuel rod needles up to the smaller diameter allowing for more fuel. I have an 8 ingh spring installed now so when vac is below 8" it should step up. 8" is the highest available number.

I dont believe vac ever gets that low during easy accel. The step up springs are designed to eliminate cruise to WOT transition bogs not dead stop easy accel bogs...as far as I can tell its running off the accelerator pump only so as soon as you stop rolling on the gas it falls on its face if you are still demanding power form it (letting clutch out) and throttle position remains stationary but rpms are adequate.

I should take video of the whole damn thing so we can analyze rpm vs vac vs AF in slow mo

 

I think iphone makes an app for it.

 

for OBDII systems right?