Spongy brakes, 914-4 brakes won't firm up??! Options

[Gearren]

I've had it! I have done everything to the brakes on my car, and I can't seem to get them to stop the car with authority. Best I get is a reluctant coast to a stop. Hardly suitable for street use! I have owned the 73 2.0 since new, and have kept it in the garage since 85. Brakes have always been weak, so as I starterd on the quest to revive the car, the brakes were top on the list. I have rebuilt both front and rear calipers, turned the rotors, new pads, new M/C (17mm), bled the m/c, bled the prop valve, and bled the system at least 10 times! I still have weak/spongy brakes! I want to keep the car stock, however I am tempted to remove the prop valve to see if it is the culprit. Any ideas or suggestions would be appreciated??

[ArtechnikA]

You're saying that Haynes is 2x too large a clearance?

...I am using Dot 3 brake fluid (Prestone), could the fluid be a contributor?

I've read some threads about losing the prop valve and installing a "T" fitting, and it seems like an
interesting idea.

yes. 0,004" seems to be about right.

DOT 3 is not appropriate for disc brake systems.
DOT 4 is. there are lots of goot ones that work just fine available at the FLAPS - that's where i get my Valvoline SynPower fluid, and Castrol (might be labelled Lockheed/Girling) LMA/GT works.

the proportioner valve keeps the rear brakes from locking up first, which is A Bad Thing.
i pitched mine years ago, but it was a /6, and i uprated the front calipers, so the overall balance remained about the same. if you go that route, just be real careful about putting heavy stuff up front while leaving the back trunk empty ...