1970s Power servo rotary valve

[rms70]

Been working on the climate control to get at least heat into cabin.(hasn't worked since restarted car in 2020 after 20plus years in storage). This led to an engine and radiator flush, new heater core,new hoses,new water control valve and buying Cadillac Tim's book. The book is great, really makes the complicated system understandable. Worked on in dash unit first and found rotary valve grooves filled with metallic dust. I reconditioned the valve according to the book directions but couldn't get it to stop leaking vacuum. I blamed it on the rectangular retaining spring that holds the two halves together which I deformed when I took the halves apart. Tim  sold me a dash valve he had reconditioned and after the struggle of putting everything back together the dash unit now sends a solid 17 inches of vacuum to the system. The vacuum feed up to the power servo  is the same 17 inches to port four but when calling for heat(rotary valve rotated by the diaphragm pulling arm in) there is no vacuum at port 2 which would open the water control valve. This rotary valve must be really warped because I've tried sanding it and leveling it a half dozen times to no avail( or  no vacuum). I'm beginning to think my fail on the in dash valve might not just have been the retaining spring. Has anyone reconditioned their valve by Cadillac Tim's method and gotten it to work? As a side note, I called Eldorado George to get some advice. He won't work on just my valve but would restore the entire servo unit, beautiful job but pricey. He also said the two valve sides must be perfect,he grinds them in a 50 thousand grit slurry and when put together dry they can't be pulled apart. When I dismantled the engine back in 1998 I remember the climate control system working, cold air and heat. I can't imagine the two valve halves were in a perfect  condition after 28 years. Anyway, if anyone has reconditioned their rotary valve how did you do it?  How did you get it flat and how did you know it was good before reinstalling it? Mine now look flat,no visible high spots or low areas but still no vacuum. If all else fails maybe Cadillac Tim has one for sale..need to do something before those nice day cold weather drives.
              Thanks,
                   Rob

[Jeff Rosansky CLC #28373]

I put mine on a piece of very fine wet/dry sandpaper on a piece of glass and sanded it in a figure 8.
It looked flat but after a couple passes you could really see how it was warped.

[klinebau]

I put mine on a piece of very fine wet/dry sandpaper on a piece of glass and sanded it in a figure 8.
It looked flat but after a couple passes you could really see how it was warped.

I did the same except I used my table saw as the flat surface.  It's been a while, but I think I did one pass each with 1000, 1500 and ending with 2000 grit paper.  Just like Jeff, you could see where it was previously warped when sanding.

[TJ Hopland]

As long as you got a nice table saw in good condition that seems like a reasonable surface to use.