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?
I would try a wet bleed to get out any trapped air. Run a tube into a jar of brake fluid and open the bleeder and pump the pedal. You can do one at a time or all four. If this does not work you may have a bad master. I had an OT Camaro that did this and it had the parking brake in the rear calipers.
If you have copper washers on the brake lines at the caliper, and have reused them, try replacing them. Had the same problem many years ago. Replaced them, no problems afterward.
If you have the master under the floor(I assume you do)sometimes it is almost impossible to get all of the air out by just manually bleeding the system. I have a friend with a 35 ford, we replaced the front calipers, we went through about a gallon of brake fluid and still could not get a hard, consistent brake pedal. I went back to his shop the following weekend with my power pressure bleeder and within 5 minutes had a good solid pedal. The problem with his car and the pressure bleeder is the carpet covered the m/c hole and he had to remove his seat and carpet so we could put the pressure bleeder adapter on the m/c.
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