help with 1967 gmc brake issues

[arcticman]

I have a 67 gmc 4x4 drums front and rear. Does this truck have a proportioning vavle? there is a block just off to the side of the master cylinder with electrical wire but no switch/pin to reset valve.The master cylinder has very thick syrup sludge so im replacing the M/C W/C and lines wondering if the block i spoke of can be flushed out or does it need replaced. If it cant be cleaned were should i look for a new one that is correct. my search only comes up with valves for front disk rear drum? Truck has manual brakes no power and im not interested in conversions

Thanks Scott

[Stocker]

Proportioning valve is for trucks with front discs, yours has a distribution block. I doubt it needs replacing, probably just flush it out.

[68Gold/white]

Originally Posted by Stocker

Proportioning valve is for trucks with front discs, yours has a distribution block. I doubt it needs replacing, probably just flush it out.

I agree.
If it were mine, to start with I'd get a new (not reman) master cylinder, thoroughly bleed all wheels. Test drive it to make sure that none of the wheel cylinders leak...

The very best fix would be to replace all the wheel cylinders. Depending upon your budget and how much you value your time....in the olden days I have seen shops take apart the wheel cylinders (while still attached to the backing plate) and used scotch brite or a wheel cyl hone to clean up the cylinders, and install new rubber parts (commonly known as wheel cylinder kits, which are cheap)

[arcticman]

I have new ACDelco M/C and W/C made in china. I would have rebuilt but cannt get kits. Thanks for the info.