I am about to get some disks, calipers, spindles, backing plates from a cutlass. You guys have convinced me into staying with manual brakes. Right now in my 69 I have manual drums all the way around.
The questions are:
Can I use my same master cylinder? How do I know what size I have now? Or do I have to get a new 1" bore specific master.

Can I used my same p valve? or take the one off the powered disk car?

You will need a different M/C. And the proportioning valve of the donor car.
Hope this help. sean

SAyers69 is right. You will need a disc/drum M/C, which will not have a residual pressure valve on the front lines. And you do want a 1" bore to give higher pressure (to compensate for the lack of a booster).

You also need a combo valve. What you have now for a 4-wheel drum system is not a proportioning valve, it is simply a distribution valve.

Check out these useful pages from master power brakes: http://www.mpbrakes.com/what's2.htm http://www.mpbrakes.com/mpfaqmasters.htm http://www.mpbrakes.com/mpfaqdiscs.htm http://www.mpbrakes.com/mpfaqvalving.htm

You can also keep the distribution valve that you have now & put an adjustable proportioning valve in your line going to your rear brakes to cut down the pressure going to them.

I just put front manual disc on my car last week, get a master cyliner for a 67 camaro and use the combination valve from the donor car and you'll be set.

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68 468 700R4, and here it is;
mutert23 (http://home.earthlink.net/~mutert23/)