Front brakes grabbing again.

Man o man...I'm getting tired of this one. OK....all brake lines replaced. MC replaced. Wheel Cylinders replaced. Splitter replaced. I installed brake lines away from headers to avoid heat. I bled the system like mad over and over again. I removed MC to make sure the pushrod is at the correct length connected to the brake pedal (OK) and My Front Brakes Are STILL Grabbing!!!

Anyone have any idea what the hell I need to do. What can be causing these brakes to grab? It has to be a pressure issue because as soon as I crack open bleeder valve on MC.....I can actually hear the front brakes release....it's as if the fluid isn't retaining back when brakes are released.

I can go out to car now and pump brakes 100 times and they will catch and release fine but it's when I go out for a ride this happens. Also, ...it's not as bad as it was before I replaced the lines....the grabbing would begin much sooner than it does now. Since I have MC out of vehicle, I'll be doing another bench bleed but any other suggestion? Is it as simple as air in the lines?? Someone help for the love of Nazareth. Thanks. Oh...car is a 65 Pontiac LeMans GTO clone. 4 wheel drum brakes single reservoir MC.  

Hopefully I can help. I just went through it myself. For starters, always replace your cylinders in pairs.  Same supplier.  The one you didn’t replace could be the trouble if the other 3 were swapped.  Make sure you are using good quality new shoe return springs and put a little smudge of grease on the specific small area on the drum back plate to keep the shoe travel from hanging up from friction. Be careful of course not to get any grease on the shoe material- just the edge of the metal that the shoe material is bonded to.  Also, make sure your back plates are clean and rust free. Once I completely cleaned and painted my drum back plates and put in all new fresh springs and shoes with a little lube on the plate in the specific area that you grease, they work great and return every time.  Also, make sure your shoes aren’t in backwards.  It’s very easy to do, and when I first rebuilt my front drums, I notice that there were in backwards before I started. You can also try to bleed the Master while in the car by having someone press the pedal while you loosen the brake line retaining nuts about 1 turn and then tight again.  I did this and got air bubbles, plus a little rusty dirt that was trapped inside- even after bleeding the system through the wheel cylinders several times and starting with fresh fluid. My master was only a year old per the previous owner- but you know how that story goes.  In all honesty, it sounds like weak return spring hardware and/or the surface between the edge of the shoe (not the shoe material, but the metal that it is bonded to) and the back plate binding or getting stuck in its travel.  Good luck.  
1969 Custom S