Ok I'm lost, I had to take the brake line off my 32' Roadster to make some repairs. When I returned to bleed the bakes last week I could not get a hard pedal. I could pump them up and have a decent pedal but than if I waited a couple minutes , strait to the floor. I've tried a new M/C . I bench bled it well. bled all four corners and have zero air coming out. I've gone through the car to make sure there are no air or fluid leaks . I did replace the Proportioning valve (screw in style) before I started this. and it is fully open. The car had excellent brakes prior to this. It has four wheel power disc. 7" booster and Corvette 1"M/C .Any thoughts?