65 Barracuda Brake Distribution Block Woes

The seal is made between the flare on the tube and the tapered seat in the block. No teflon tape or sealer here! You can try removing the leaking tubes and inspect them for defects in the sesl area. Also, the seats must be good. Try using a magnifying glass if needed. You can use fine sandpaper to dress the flare surface lightly.

What usually works for me is: tighten the fitting, loosen. Tighten again a little more past the first location, loosen again. Repeat this several times. Similar to hand lapping valves. I do this on all my new connections and it seems to work pretty well.

But the washers mentioned in post #2 could work if you still don't have any luck.

But it sounds and looks like you are not updating to a dual master cylinder. If ANY of your lines spring a leak, you could have no brakes. I used a dual MC for a 67 a body when I redid my 64 brakes.