68 barracuda with 74 dart sport disc conversion, working well until I changed front brake hoses, and now can't get any pedal after bleeding. I swapped the master cylinder thinking it may have been bad, no better. Changed the rear wheel cylinders as they were bleeding kind of slow, still nothing. I have fluid and no air at all four wheels when bleeding. Any ideas?

did you bleed the master cylinder?

If not you may have air in it.

Bench bled the MC before putting it on, seemed to be done correctly with no air left

Did you use the 74 combination valve? If so the shuttle might be over to one side blocking flow, you may need to recenter it.

Yeah, it's the proportioning valve out of the dart as well, but would that cause the pedal to go to the floor? I haven't adjusted it at all, what would cause it to go out of center?

you did the conversion & all was well for a period of time then later on you changed the front hoses & the prob started? As said (1) bleed the MC (2) bleed the fronts (3) bleed rears if needed. put a block of wood under the pedal so it only goes to ~where it depressed to when it was good. there are speed bleeders but an old fashioned helper works good for bleeding

Sounds like a good idea, I'll give it a shot re-bleeding master
Cylinder and use a block of wood as a spacer. Hope to get it done this weekend, I'll keep you all posted. Thanks

Bleeder on top of caliper?

Gravity bleed them!

I'm guilty of that