Should an automatic valve body th350 manually shift normal with no vacuum source.

[dville_gt]

The th350 I am running behind the lq9 is a built trans but does not have a manual valve body. I totally forgot to hook up the vacuum modulator. Today when I took it for a cruise it would not shift correctly even with me manually shifting. It did go into second a couple of time part throttle, but sometimes it wouldn't and it never went into third (although my max speed was only 30-35mph so that might have something to do with it)

I was under the impression that the trans would shift fine manually even with no vacuum source (even with a auto valve body), is this incorrect? Does it need vacuum source for part throttle manual shifts?

[R3_82GT]

It's been a lot of years since I've messed with a Turbo 350, but I'm real sure you need manifold vacum to the vacuam modulator for it to shift right. Maybe this will help:

http://www.tciauto.com/Products/TechInfo/FAQ.asp#13

[junk racing]

It needs vaccume to operate correctly....

[Bigcountry]

Why not use a manual valve body? Just curious.

[dville_gt]

Had this trans in storage, it worked great behind my lt1 that was built for a while. Figured I'd throw it in here and see how long it'll last. Only worry has been that it could have gotten wet in storage. That's why I am concerned but it sounds like I should hook up vacuum before I rush to judgement.

[turbostang]

I don't know the technical explination, but yes it does need vacuum to shift in a timely manner. If it's not hooked up the shift points will be WAY high - the same reason you never got into 3rd. The same reason that the 1-2 shift was wierd.

[dville_gt]

Spot on Brooks, got the line hooked up and it seems to be working just fine. Figured if I was going to manually shift it, it didn't matter. Whoops, it is nice that I can throw it in 3rd and it will drive itself around as well.