Hot Rods I need brake help guys

Speedfreak, just to be sure, you do have the MC rear reservoir going to the front brakes correct? And, the 2psi residual valve in that line. I'm still thinking the rod is to long in the master cylinder, and the piston is not moving back enough and clearing the port to release the brakes. If you are positive there is enough movement of the piston, I would replace the MC. I am also assuming the brakes have never worked properly since you installed the Mustang II rack and brakes, correct?

 

I had a similar issue, but my master is on the fire wall....the 2 lb residual was my issue...removed it and put just a coupling in its place...no more issue...

 

As others have stated, pull the master from the booster and measure the length of the push rod coming out of the booster. Then measure the depth of the piston on the master and you should have a small amount of clearance. Another way to check is get the brakes to drag then simply loosen the master from the booster and see if they release. Is there a pedal mounted brake light switch that could be preventing the pedal from returning?

 

i had the same problem on my 35 truck. it was a bad booster. disconnect the hose from the booster and drive it . and see if it still locks up..[ as dumb as it sounds mine was building pressuer and and locking up the brakes within 3 miles]

 

I had a bad hose do that also. It would let fluid in but was restricted going back to the master. After a few stops the brakes would be dragging.

 

Nasty problem, you said the front brakes drug, you cracked the line at the MC and released the pressue - there was positive pressure in the line at the master cylinder? and the brakes released? Is that correct?
I would have blamed a swollen hose until you did the above, the problem could be the booster is keeping pressure on the MC when the pedal is released, try to pull the vacuum line off it the next time and see what happens.
Do you have the rear brakes plumbed into the MC at the rearmost port and front brakes at forward ports - I ask because the rear brake is applied first and then the front, if the piston isn't returning fully it should be the rear brakes seeing pressure rather than the front.
One other question, do you have the front brakes plumbed seperate lines from the MC/prop valve or is there a 'tee' in the line?
Is it synthetic fluid or silicon fluid? has it had synthetic and then changed to silicon?