Ok I read Till I am blue in the face.. Can not find info I thought I read at one time. So my after market front disc brakes are hard to turn. If you crack the line at the master cy. they become easy to turn.Or let it set for 2-3 days. I think I read somewhere that if you take the line seat out. there is a valve under it you can take out. this was a drum brake master cy.Brakes work great. But going to wear out the pads and it is hard to push the car. This is a 66 coronet with a 67 master cy on it.

I WOULD say that you have a bad rubber line/hose at the wheel; but you say BOTH are hard to turn?

if that was true cracking the line at the master cy would not change it.

Yeah, you're right.

Get a master for a 70 C body disc brake car.All we run on conversions.Mine from Advance was like 20 bucks or so.Used the same on the charger and the 62 300.If power the pushrod under the master is adjustable.Rocky

Is the '67 MC a disc brake MC? A disc brake MC won't have the residual pressure valve behind the line seat.

Make sure the rear piston in the MC is fully returning when the pedal is released. If pushrod adjustment is preventing the piston from fully returning it will trap pressure in the system when the pedal is released.

If it was a drum/drum master cylinder, you have to remove the residual check valve out of the master cylinder for the reservoir that feeds the front brakes, should be the rear reservoir. Found this info. You are right John.

^^^This makes sense..you should be able to take the cover off the MC, then have some watch while you depress the brake pedal hard. Then release quickly and you should see backflow in the fluid if the hole is uncovered.

DON'T forget to throw a fender cover on.

If you probe into the master cylinder port with a small drill bit and feel something springy, that would be a RPV, which would need to be removed.

Power brakes? Next time it locks up, unbolt the master from the booster and see if that relieves the pressure. If so, the pushrod needs to be adjusted shorter, like John was hinting at.

No power brakes. I need to remove that RPV

Easiest way to remove the seat is to thread a screw into the hole and pry it out with a claw hammer. Careful not to damage the sealing surface when reinstalling.

Got it done ! Thanks

Just to let everyone know. that did fix it