I installed wildwood discbrakes on my 71 dart do I also have to change mastercylnder it seems that the master cylinder is not working right I have to pump brakes for it to work or the orinal equipment pump is not for disc brakes thanks need help

I assume you still have drum rears with disc fronts...
what size is the master... did you TOTALLY bleed the
system... if you have to pump the pedal does it get
hard and stay hard... if so your master is too small

Did you remove the residual valve from the master cylinder that feeds the front end brake line(rear reservoir) and disc brakes ? If not do that first and see how that helps Normally the standard drum brale master cylinders have two residaul valve in them, the standard disc brake master cylinders have one for the rear drum brakes only, which is noramlly the smaller front reservior on the master cylinders. The stock disc brake master cylinders have two different size reservoirs, small front for the rear dums with the residual valve and larger rear reservoir with no residual vavle for the disc brakes on the front

Call Dr. Diff and he will set you in the right direction. I just converted and put on the Cardone 1 1/16 bore and was not happy with the hard peddle. Just ordered a 15/16 from Dr. Diff, but did not put on yet. You should probably have a proptioning valve to the rear also.

Go to this site and feed in your info. Do the math one time and get it right. You'll be happy.
http://www.markwilliams.com/braketech.aspx
Doug