Brake Issues

[Darkness_is_spreading]

I have a 83 Jetta, that has new brakes/lines, front to rear and this includes a new master cylinder.

I am having issues with the amount of pedal travel or lack of pressure when I apply the brakes.
The MC was bench bled until fluid came out of the master cylinder at each port.
The MC was then transported to the car with awaiting brake lines.

After checking all of the brake lines to make sure they were tight, I began bleeding the brakes from the pasenger rear drum, until I seen fluid comming out. I bled the brakes as indicated in the bently, until I had clean fluid and no air bubbles. The pedal has some force, but my father indicated to me that the pedal resistance was low and possibly their is an issue with the brake system. So today, I again re-bled the system, and to no avail, the brakes seemed to be lacking in resistance.

Is it possible the new MC is bunk? Or is it possible the master has air trapped in it?

I also checked on the car and noticed that it does not have a brake proportional valve....  I believe this may be one of the main issues with the system....
Can an aftermarket adjustable proportional valve be installed? 

[R.O.R-2.0]

I have a 83 Jetta, that has new brakes/lines, front to rear and this includes a new master cylinder.

I am having issues with the amount of pedal travel or lack of pressure when I apply the brakes.
The MC was bench bled until fluid came out of the master cylinder at each port.
The MC was then transported to the car with awaiting brake lines.

After checking all of the brake lines to make sure they were tight, I began bleeding the brakes from the pasenger rear drum, until I seen fluid comming out. I bled the brakes as indicated in the bently, until I had clean fluid and no air bubbles. The pedal has some force, but my father indicated to me that the pedal resistance was low and possibly their is an issue with the brake system. So today, I again re-bled the system, and to no avail, the brakes seemed to be lacking in resistance.

Is it possible the new MC is bunk? Or is it possible the master has air trapped in it?

I also checked on the car and noticed that it does not have a brake proportional valve....  I believe this may be one of the main issues with the system....
Can an aftermarket adjustable proportional valve be installed? 

car definitely has a proportioning valve, and thats usually where the air gets trapped..

the prop valves are either connected to the MC, directly under the MC, or back under the drivers side of the car, in front of the tire..

ive always had to zip tie the valves open to get them to bleed right..

(it is completely possible that you bought a junk MC also)

[clbanman]

Is it truly a new master cylinder or rebuilt?   I've had rebuilt ones in the past that would not build good pressure.   My hypothesis is that they honed them out too far and it was allowing leakage past the seals.  No idea what level of quality control the rebuilders have, but I'm sure that they would not do 100% testing.