I bought a car that last owner converted to disc brakes(front).He only replaced drums to discs, so now I need a proportioning valve right? Are the distribution blocks the same on drum and disc cars? Do I need a metering valve to? Thanks!
Most disc/drum systems require a prop valve to keep the rears from early sliding under hard/wet braking. I would recommend an adjustable valve, not a fixed-value OE production valve. I would not use any distribution blocks or metering valves. Keep it simple-a 2 lb residual to the fronts (ONLY if the master is floor mounted), a 10 lb residual to the rear drums (if the master does not already have an internal valve in the rear port), along with the adjustable prop valve. This assumes a dual master, yes?
You can use the single pot rez with 2lb and 10lb residual valves, I've been doing it for years and never had a problem, but I also have a 76 coronet rearend under my 48 dodge with better drums than original.
I converted my 65 Dart to disc on the front and used everything from a 73-76 dart including the proportioning valve. But a adjustable one would be pretty nice. I'm still using the same drum brakes from the 65 on the rear...though I probably should upgrade to the 73-76 bigger drums...since I do have them. But mine stops darn good and I can't get them to lock up no matter what. Which I think is a good thing.
Most/all single masters have an internal residual with too much pressure for discs, and should be removed. Also, most single chamber masters do not have the necessary fluid reservoir volume for disc brakes. Add the fact original pre-'67 masters can be hard to find and can cost more than a '67-up dual. There's really no good reason not to change to a safer/modern dual master cylinder when upgrading the brake system.
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