Need Help with Powerglide vacuum line

[Metalaroundstone]

Hi guys,
I could use a little help figuring out how the vacuum line from my Powerglide transmission in my 66 with a 327 should hook up to my engine vacuum. What is currently there seems very strange to me. The tubing from the trans seems to require 5/32 vacuum line, but it hooks up to a section of metal tubing that is sized for 9/32 tubing, which then connects to a 5/16 vacuum tee on the intake manifold. It is clear that all this is to up-size the vacuum hose from 5/32 from the transmission line to 5/16 port on the vacuum tee on the manifold.

My question is this: How should this vacuum line be handled to match how it was done at the factory? Is what I have makeshift or does this somehow match how it was done originally?

I can't seem to find any illustrations about this. Any help will be greatly appreciated. Thanks

[WHAMMY'DWONDER]

Hey man I have a 66 w a pg and mine goes from one size to a bigger size also, mine has power brakes and the line from the trans goes to the power brake booster. Seemed funky to me but talked to an old timer tranny builder and he said it was how it was originally. Mine had a bad rubber hose and my tranny would not shift out of first gear but once fixed shifted into drive. Also old timer trans guy said the kickdown on a powerglide dictates shift point too. Just food for thought, a out of adjustment kickdown will let it shift too early or not at all .Not sure I answered your question lol.

[Metalaroundstone]

Originally Posted by WHAMMY'DWONDER

Hey man I have a 66 w a pg and mine goes from one size to a bigger size also, mine has power brakes and the line from the trans goes to the power brake booster. Seemed funky to me but talked to an old timer tranny builder and he said it was how it was originally. Mine had a bad rubber hose and my tranny would not shift out of first gear but once fixed shifted into drive. Also old timer trans guy said the kickdown on a powerglide dictates shift point too. Just food for thought, a out of adjustment kickdown will let it shift too early or not at all .Not sure I answered your question lol.

Thanks for the response. It is hard to believe that what I have is stock. I wonder what the function of the steel tubing is and why it loops up and then down again before connecting to the fitting on the intake manifold. It seems like it would be much simpler if the fitting on the intake manifold was the same size as the tubing from the transmission so a single 5/32 vacuum line could span the gap. Anybody else have any experience with this?

[Wrenchbender Ret]

It loops up so any gas that got into the line would drain back & not ruin the modulator diaphragm. Originally the narrow tube fit into the larger tube with a short piece of hose to seal them.

[Metalaroundstone]

Originally Posted by Wrenchbender Ret

It loops up so any gas that got into the line would drain back & not ruin the modulator diaphragm. Originally the narrow tube fit into the larger tube with a short piece of hose to seal them.

Thanks for info. I guess I won't mess with it.