Hi All, I'm stumped on this one and could use some help. I swapped the stock kelsey hayes power disk brakes from a 1972 dart onto my 1963 valiant. Along with the swap I did a full rebuild of the front suspension with firm feel parts so I have the correct lower ball joints.

I used the proportioning valve from the 1972 dart and removed the old 4 wheel drum brake distribution block.

When I stand on the brakes I can push them basically to the end of their travel easily. I do have braking force but it is very weak, like not a chance I'll drive it weak.

The pedal feel is not any harder when the car is off as is usually the case with my other power brake mopars.

The master cylinder is a new raybestos MC36426 which shows as correct for the car with a 1_1/32nd bore.

The casting number on the bottom of the master appears to be 29893-C which I can't seem to cross reference to anything.

The rear is the stock 7_1/4 with 9" drums for now. The drum pads are low on material but the brakes bleed out fine and I replaced the wheel cylinders.

I've bled the bejeezus out of the system and have clear fluid at all four wheels. I kept going corner to corner bleeding until I had used 1.5x of the big bottles of brake fluid.

There are no visual leaks anywhere including in between the master cylinder and booster.

I'm using the stock 1963 brake pedal connected to the pushrod from the 1972 dart booster.

The pushrod between the booster and master is the original from the 1972 dart.

The bleeders on the calipers are pointing up.

Nothing makes any funny sounds.

The only things I can figure are I got a bad master cylinder that somehow is bad but doesn't leak, or I got a weird master cylinder in the wrong box with a tiny bore so I'm not pushing enough fluid.

Any and all input appreciated!

Help!!

-Jon
[img:left]https://photos.app.goo.gl/KcEjnDYw0Kr48uc12[/img]