I can't seem to get the brakes to bleed on dad's car. No matter what I do the brake peddle is still mush, it goes right to the floor and the car barely stops. The system is all new including the lines, except for the rear flex line and back. Here's the system, 7" booster and master under the floor, Wildwood adjustable proportioning valve, residual valves, disc brakes up front and a 57 Chev rear end. I've checked the system front to back for any leaks, fixed the couple that were there. Because the master is under the floor I'm using the push and bleed method instead of pumping the pedal. What the hell am I doing wrong?