I just converted to front manual disc brakes on my 66. I have bled the brakes but I ran into a problem. If the MC cap is fully on then I can only pump my brakes once before the pressure goes out. I found that if I then take off the MC cap and put it back on then my brakes will work great. that is until I bleed. after that the pedal and pressure gets poor. Then if I remove the cap again everything is fine, until I bled again. anyone have some help?

Never mind on this post. It was somehow the master cylinder. I replaced it and they work great. But if you want to help then head over to the electrical and wiring forum and read my post there.