I've already converted my front shoe brakes to disc from a a doner 73 duster. I've installed all new parts including new shoes, pads, rear drum cylinders, new kits in both calipers, new master cylinder and rebuilt the original proportioning valve out of the doner car. I've bled the brakes till I'm just about bled out,
still have about 4" of pedal travel unless you pump up the brakes, then they are nice and solid. I've verified there is no air in the system, I've installed a clear tube onto the air bleeders and the fluid is coming out solid and clean with no bubbles. The master cylinder is a new (rebuilt) exact part that was originally on the duster. It's manual front disc brakes. It seems to be the disc brake half of the MC that's not doing what it should, what am I missing?