I currently have a proportioning valve, not sure about the residual. Thanks for the information. Harold

Replacing a drum/drum master cylinder often is recommended, one of the reasons for which is that drum/drum master cylinders typically have smaller bores. However, my original 55 Tbird's master cylinder had a 1-inch bore. Although it had manual brakes, I'm pretty sure that the same master cylinder was used for cars equipped with power brakes. However, Wilwood recommended a 15/16ths bore for my disc/drum application; that's what I bought. 

Some master cylinders have an integral residual valve. There are some recommendations for a 2-lb. residual valve for front discs and 10 lb. for rear drums. Wilwood only recommended the residual valve for the rear drums. 

I used Wilwood's also on our 1956 Victoria. I did not want was a vacuum can on my firewall and they suggested their smallest diameter MC and to install smaller wheel cylinders on the rear drum brakes I had added with a 8.8 rear install. Everything went fine and I'm pleased. The pedal pressure is less than the original 4 drums but not touchy like power assist. They recommended an adjustable push rod from a Mustang. I bought everything from Summit at their suggestion to save a few dollars.. I am local to them and their technical support for me was top notch.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

Typically, drum/drum master have an integral residual pressure valve, even the dual bowl units. .  Disc/drum masters do not have it and that is why most, if not all systems, use a separate  combination valve (residual pressure, balance valve) .  One seems to be shown in the picture posted.  

54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

Well, RPV(s) were standard on either a DUAL RESERVOIR DRUM-DRUM or DISC/DRUM (drum brake circuit) until about 1972 when FORD deleted the RPV and went to drum wheel cylinders using a cup expander design. As you can no longer buy original FORD (other than NOS) the aftermarkets may come through with or without. You have to know.

Same with a METERING VALVE as FORD changed MC calibration to negate them.

A 2# RPV on a DISC circuit is only used when the caliper is mounted below MC level.

The standard bore/piston size for a K-H design 4-piston caliper MC is 1 inch unless the car was/is a HP car.

The system has to have an adjustable PPV valve to control weight bias, especially in a panic stop situation. A METERING VALVE is suggested for proper performance and front pad longevity.

WILWOOD does not offer power assist so if wanted has to be sourced from another vendor.

1957 FORD DRUM/DRUM manual MC bore size was 1" while power assist was 1 1/8"

You have to cipher exactly what it is you are trying to do and plan/buy from there.

Using GM style braking system(s) is a completely different story.

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The Master Cylinder was installed many years ago, maybe from NAPA. I was told by the Wilwood guy to use 3/16" brake line instead of the 1/4". Any comments. Thanks. Harold

WILWOOD was correct about line sizing (IMO).

What you are trying to do is update the original braking system to a later design. It would be best (IMO) to also use whatever line size as used on the later design system for retrofit. But shoe size and wheel cylinder size(s) also come into play here.

Did I read an earlier post correctly saying you have a PROPORTIONING VALVE in the present system?

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I installed the disc brake kit purchased from Hills for my 55 Tbird.  The kit was developed by a guy that retired and Hills now sells it.  The parts seem to be repro Ford and most parts arrived in NAPA boxes (part numbers removed). My car had power brakes.  After installing the kit, I thought the discs needed more pedal pressure to stop comfortably.  I installed a Midland C490 booster (recommended by Hills) and it improved the stopping power eliminating the need for the heavy leg pressure required for the "final" stop.  That booster was designed for a Dodge truck.  It's out of production expensive hard to find.  They do come up on eBay usually $1,000.   It has a larger vacuum can, smaller piston with longer throw to produce more pressure