Customer car 1970 Demon street/strip.
Just installed a new manual disc brake conversion brake kit from The Right Stuff.
Front brakes and master cylinder.
Installation was smooth.
*** Only propo valve in system is a manual for the rear brakes ***
Retained rear drums
Bled system several times via gravity, back bleed, then pressure bleed.
The front calipers retain pressure, thus dragging the rotors. I crack the bleeder, a little spurt, then the rotor turns freely.
Pump the brakes a couple of times and they lock up until I open the bleeder to get that little spurt.
Calipers are plumbed direct from M/C into a T then to each wheel.
Rear drums do not lock up.
Any ideas ?
The Right Stuff is now owned by Restoration Parts Unlimited and they offer zero tech assistance on their website.

D -

Off the top of my head: is there a proportioning valve, and was it set up correctly?

Archer

Only propo valve in system is a manual for the rear brakes

Is the piston in the master cylinder releasing all the way? Just wondering if the rod on the brake pedal needs to be shortened a little.

I Agree with five points..... Also double check the flex hoses to make sure they are not working as a one way check valve... If that's all good I would say you have to remove or change to a lower residual valve setting.