I have a power brake boost master combo in the original location. mustang II front disc brakes, gm drum brakes rear. i do have residual check valves in place but no proportioning valve on the rear brakes. I have carefully pumped at least two quarts of brake fluid through the system and still no pressure at the pedal. i have adjusted the rear drums and see no air coming out of the tubes as the fluid is going into the catch bottle. Any thoughts?
