Technical Brakes Hangin Up

I have a 1954 Chevy 210 that I just finished building, It's got a Mustang 2 front end with new stock calipers, new stock 54 chevy manual master cylinder, and all new brake lines. The front calipers lock up and will not release until you let it sit for a few minutes. I've already taken apart the brake lines and blown them out to make sure there's no trash in them and the T's as well but the problem persists, it still holds pressure. I cant figure it out because a buddy of mine had the same setup on his 54 and the brakes worked perfect. I planned to drive my car to the Lonestar Roundup next weekend so I'm kinda in a bind. I'd appreciate any advice as to what might be causing this.
-Thanks

 

drum brake MC should have residual line pressure valves, no idea what your MC looks like but see if you have a rubber valve in the MC where the pipe screws in. If its a one line out type chuck it and fit a proper (and safer) dual MC.

 

I had this problem on Chevy discs where the banjo fitting bolt bottomed out in the caliper. I ground a little off the end of the bolt and that fixed the problem. No other troubles for the next 20 years, still working great.

 

Your buddy has the same set up ? Factory stock 54 Chevy master too?
Did he pull the residual valve out of it ?

That master has built in residual valve and it seems to be working correctly by holding the pressure that drum brakes require.

 

could be the rubber brake hose(s) are old and collapsed.