I have a 1968 camaro with power 4 wheel disc brakes. I replace the rear disc brakes because one puck was stuck in and wouldn't extend and my master cylinder was leaking. I bench bled the mc and replaced the rear brake calipers . I have bled the brakes about 8 times and the mc about 3, using the bleed ports on the mc. Every time I have have stiff pedals and feels good. I start the car and the pedal goes to the floor. I have the car on stands put it in drive and the rotors don't even slow down any. I adjusted the emergency brake to where I push on the lever I can't hand turn the rotor. It sounds like air but after bleeding it that many times I figured it would be out by now. No leaks on any connections. Thank you for any replies.