I installed a dual master cylinder on my 1964 Avanti while I was also adding modern style disc brakes. After hitting the brakes the calipers are locking up. First I suspected that I did not adjust the rod going into the master cylinder to the correct length but double checked it and it is fine. I can also tell that is not the problem since I can take the master cylinder off of the power booster and they are still locked up. If I crack the front brake line where it goes in the master cylinder the rotors turn fine. I used the master cylinder that is called out on Bob Johnstone's site that is supposed to fit Chrysler A, B, and C body cars 1967 to 1970 with drum brakes (NAPA part #ts101323). When I look up residual valve info on the internet it told me that a drum brake system residual valve will not work properly on a disc brake conversion. Does anyone know if that type of master cylinder does use a residual valve and if so can I remove them as shown on Bob Johnstone's site? I do like this type of master cylinder since it has a bolted down cap on it instead of the spring loaded wire clip type and is low profile so it clears the hood.