Disc brake conversion help

My car was originally all drums, no power. Its now a manual setup with front discs. The new master is for like a 72 nova w/ discs. I put it right in place of the old one, didnt touch anything else. Rear brakes wont work now and very little pedal.
What is that valve thing in the brake line under the master? I dont think its a proportioning valve? or is it? Is it a safety valve that if the back loses pressure the fronts get more?

What can i do to get my brakes to work? Take this out? Should I need anything there? Proportioning valve? Or just hook the lines right up from the wheels to the master nothing in between?

It allows the front to get more preasure(proportioning).I think you may need a different lenght rod when not using the booster(longer I think).Both my 69's have power disc 68 was the only year that came manual disc.

It allows the front to get more preasure(proportioning).I think you may need a different lenght rod when not using the booster(longer I think).Both my 69's have power disc 68 was the only year that came manual disc.

So do I need the valve or just take it off?
Rod was adjustable, works fine.

Hi Pwrtrip75,

On drum brake cars that "valve" under the master cylinder is simply a pressure switch that activates the "BRAKE" light on the dash if either the front or rear brakes loose pressure. The front/rear proportioning on drum brakes is handled mostly by the sizing of the wheel cylinders.

Those switches are normally self resetting once the problem (such as a leak) has been fixed. However, they can sometimes stick and might possibly block fluid flow. They can be reset manually by unscrewing the electrical contact (where the wire plugs on) and re-centering the sliding spool valve down inside using a small screwdriver or similar tool to reach in the hole. After doing this you'll probably still need to bleed the rear brakes in order to get them working.

The setup you have now should work okay with the disc brakes under normal conditions. But you should really consider adding a proportioning valve to keep the rear brakes from locking up during a "panic" stop. You can do that by adding an aftermarket adjustable proportioning valve inline with the rear brake line (after the pressure switch). Or you can replace that pressure switch with a combination valve ... like the ones GM originally used on most 71-up vehicles with factory disc brakes. The combination valves have the pressure switch (for the warning light) along with a proportioning valve built into the same housing. They also include a metering valve that slightly delays application the front disc brakes while the rear shoes move out to contact the drums. Having the rear brakes engage slightly before the front helps with directional stability during braking.

So do I need the valve or just take it off?
Rod was adjustable, works fine.

I wouldn't recommend removing it,but I no expert on brakes.I don't think you'll get enough pressure to the fronts without it.