Tuning a DD 383 for optimum mileage / 1/4 mile performance

Take fuel away from the primary jet till it surges at cruise, then go up 1 or 2 jet sizes for optimum cruise. Add fuel to the PVCR for WOT max MPH. I have found around .003 increase in PVCR is close to 1 primary jet size.

What is PVCR?
Power Valve? I have it sized by 1/2 of my idle vacuum.