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I checked into the "hunting condition" which mine has sometimes.....GM installed a vacuum restrictor in-line before the vacuum switch....it looks like a one-way check valve but it has a tiny hole in the center of the diaphragm to buffer the "oscilating" vacuum. The one I found at a salvage yard was damaged/broken open---the hole was about .010" in diameter---about the size of a single strand in a dash wire.
I think I'll get a common "straight pin".......heat the end of it....insert it into the port....and make a small hole in the one-way check valve that I bought a while back.....and install it "backwards" so it works like a vacuum restrictor.
Last edited by doorgunner; Mar 19, 2015 at 06:48 AM.
i'm happy with my mish mash controller, and it mounted of the brake booster stud, up alongside the fuse panel and steering column.
out of the way, but still easy enough to get to to adjust the speed setting, if i crawl on the floor..
see my setup is not complicated at all...
and i'm no electrical engineer, just a fitter n turner/toolmaker
but i know enough not to get myself electrocuted or let the smoke out
Last edited by riverracer au; Mar 21, 2015 at 08:00 PM.
Reason: LED reversed
I was under the impression that the TH200.4R and the TH400 were dimensionally interchangeable and that the original TH400 tailshaft, er "driveshaft" could be re-used when changing to a TH200.4R, but your drawing implies that a longer driveshaft would be needed, even though the transmission mount is in the same position. Can anyone shed some light on this please?
My 75 had a TH400 that I removed for the 2004R, the original drive shaft worked just right. I had to use a slip yoke from a vette with a TH350 or Powerglide. By the chart, the 2004R would be 3/4" shorter than the TH400, no mod is required.
I know this is an old thread, but I'm posting to say thank you! I just put my new motor and 700r4 trans in the car today and the mod you described for the crossmember (74 stock th400) worked perfectly! I only had to extend the slots by 5/8 inch.
The dremmel and grinder worked perfectly. The tailshaft housing came from the local pick 'n pull yard for $25 bucks. I can't wait to drive this puppy!
Last edited by Cool bean; Nov 22, 2016 at 05:44 PM.
