I just completed building a little hot rod with four wheel disc (kit-Chev) brakes. All new parts through-out. With rear wheels on stands off ground, pressing brake pedal does not stop wheels when in drive gear at idle. Pumping pedal does not slow wheels (posi-traction) to a stop. Have bled system multiple times, master cyl. full. I also have a adjustable prop. valve but don't know which way to adjust it..in or out. Have not done a run out for fear of not stopping and wrecking the car. HELP PLEASE. I'm a beginner!
I assume you have a brake pedal that does not go together the floor. With rear wheels on stands the proportioning valve will think the car is in a hard stop situation and not allow the rear wheels to give full braking. Try supporting the same ear at the axle so the wheels are up under the car as they would be while on the he ground. Then the proportioning valve will allow the rear wheels to get full pressure to stop the wheels. As for the adjustment on the pro portioning valve, when the wheels are in the normal position (supported at the axles), the rear wheels should apply brakes to the rear wheels to stop them.
had a hot rod builder tell me not to use a prop valve with 4 wheel disc so I didn't no problem with the rears locking up