I was reading an old article in mopar muscle about nos brake part. the question that it brought up is when I do my kh conversion do I need to change me drum master cylinder to a disc master cylinder

Quick answer no.
Good answer yes.

It is possible to do a disc conv without changing your MC. Not changing can cause some of the following problems: mushy/over soft pedal, not enough volume for brake fluid, awful proportioning problems. There may be others. The biggie is the fluid capacity. A caliper requires a much greater volume of fluid as the piston travels with the small drum resevior you could not have enough fluid when the pads wear causing an almost complete front brake failure. My daily driver got the brake swap without a MC change and the pedal felt like an overboosted power setup. Are you wanting rock solid leg busting pedal affort or easy pedal. I assume it will be going into an a body are the brakes manual or power?

Hi stolan,

Gotta second Mcnoople...when I did my disc conversion I went cheap first and used old MC. Might as well not have been connected. However, in a recent thread I detailed how I got TWO bad new MC's in a row, and one had the larger reservoir in front, one had it in back. It wasn't til I got another newMC and got discs connected to the larger reservoir that I began to get working, ....then had been given the wrong pads for the calipers. I had metal pads and they were .034 too thick..you wouldn't think it mattered, but tolerance is .005 according to FSM. So the grabbed hard all the time til I thought of that and got "organic" . Now things work like real brakes oughta.
rock
'64d100