Reuse booster drum/drum to disk/drum?

[Mopar512Guy]

1965 Coronet 500 had drum/drum and I upgraded front to disk. Swapped out the single master with one that is for power brakes disk/drum. Installed prop valve for rear. Has internal RP valve for drum. Can not get the brakes to bleed and hold pressure. Brakes only bite with pedal all the way to the floor.

Anyone have suggestions? Has anyone successfully reused drum/drum booster for a disk/drum application?

 

[Don Frelier]

Yes I have a drum booster on my Plymouth no issues.
The booster wouldn't create a soft pedal.
Are your bleeder screws at the highest point?

Did you bench bleed the master cylinder?

 

[Geoff 2]

Disk brakes require about 50% more line pressure than drum brakes, & boosters were often upgraded to provide the extra pressure.

Make sure the rod in the booster that makes contact with the m/c piston is adjusted correctly. A big gap will result in excessive pedal travel.