74 proportioning valve

[RUNCHARGER]

What are you guys with the later cars doing for proportioning valves? Is there any repros available or do you use ones out of later cars if you need them>

[Burdar]

I soaked mine in EvapoRust which cleaned up the outside and most of the inside.  Mine had been off the car for years.(stored in a plastic tote with a lot of other parts)  The brake fluid had drained out which allowed the inside to start rusting.  The main valve assembly broke when I tried to pull it out.  I found a replacement prop valve and used the valve assembly from that one in my original one.

For those of you that have the newer valves, don't store them with all the lines disconnected.  Try keeping them filled with fluid while in storage.  It will keep the insides from rusting.  I went through a half dozen prop valves before finding one that came apart easily.  The one that came apart was still filled with fluid.  All the others were dry and rusted together. 

The best option is to restore the prop valve as soon as you remove it from the car.  Soak it in EvapoRust, disassemble it and clean it out really well.  Reassemble with new fluid and block off all the ports with plugs so it stays filled while in storage.

I used to have an 82 Cordoba.  It had a prop valve similar to my 73's valve.  I'm sure one from a late 70's or early 80's car would work.

[RUNCHARGER]

Thanks Burdar: His is wrecked already. I told him to look for one out of a later M-body or something similar.

[Cudakiller70]

@Burdar  might be better off after flushing to fill with something else other than brake fluid.
Glycol-ether (DOT 3, 4, and 5.1) brake fluids are hygroscopic (water absorbing), which means they absorb moisture from the atmosphere under normal humidity levels.

[Burdar]

I suggested brake fluid because that's what the internal seals are used to being in contact with.  I don't know if another substance would react with the seals.  The prop valve I took apart had been sitting on a shelf for years with old DOT 3 fluid in it and it came apart easily.  I think the key is to have the ports plugged.  I use DOT 5 in my Challenger.  That's what I filled my Dart's prop valve with too.(it's brass though)  Not sure if that absorbs moisture as much as DOT 3 or not.

As an aside...While I was trying to remove the stuck valve assembly from my original prop valve, I sprayed it down with PB Blaster(penetrating oil)and let it sit over night.  The next morning, the large "umbrella" type seal around the assembly had swollen up to twice its original size.  As soon as I touched it, the seal split.  Don't let those seals come into contact with penetrating oil for longer periods of time.

[RUNCHARGER]

Yes: Oil is a rubber sweller.

[Cudakiller70]

Yup, with plugs or caps I don't see how moisture could get in so that should work well.
You probably all ready know that muscle car research has parts and directions to rebuild prop valves. He was fairly quick on shipping and reasonable on price.