what proportioning valve

[trbodrt]

I'm converting my 72 dart with kh discs in the front to the later 73 bbp setup, also the rears will be converted to disc brakes with the ford 9 inch setup I have, Will I need to change my proportioning valve to an adjustable or will the stock disc/drum valve work?

 

[Wheel Chock]

You should use an adjustable valve, because the bias for the rear discs will be very different from the drums. Servo action drums vs linear action discs.

 

[BillGrissom]

I agree. I got an adjustable one for $25 on ebay. Looks identical to the $85 Summit and Wilwood one other than no logos.