I've searched and came up with nothing so i thought i'd make a new post. I recently rebuilt a 350 and attached it to a good 350 trans, problem is that it holds first gear to like 5500 rpms or more every time, 1-2 shift is real firm, 2-3 is barely noticable. From what i've read the governor needs adjusting. HOW do i adjust it ?

 

Is the vacuum line to the modulator valve hooked up? Is there a manifold vacuum source there?

 

i have the exact same problem, 2nd comes in real hard specially when i leave hard, a few weeks ago the linkage that connects to the trans even broke, now every time i hit reverse hard the plate scrapes the floor, nethign that can help this, im thinking about just going back to the old 700, since this 350 is non freeway friendly

 

Don't give up on the TH350 just yet. They are good transmissions, not as durable, but a little quicker than a TH400 for some reason. Back in my day, it was the most popular aside from a 4 spd. M-21 or M-22 Rock crusher.

This should be a simple fix. I can think of two things most likely that could be wrong.

1) No vacuum to modulator (easy fix)

2) Vacuum Modulator failure (cheap and easy fix)
Stick a qu-tip or a pipe cleaner into the vacuum connector pipe to check for the presence of trans. fluid. If oil is found the diaphragm is bad. Gas and/or water is not a problem, only oil.

The governor is doing it's thing because the governor inner weights makes it shift into 2nd at the higher RPM like you stated. Without vacuum the only thing to tell it to shift is the centrifugal force of the inner weights. You can actually take a TH350/400 and pull it into first and it will still change into second on it's own. Again due to the centrifugal force. That was an old racing trick I used, this way you didn't have to worry about watching the tach while dragging on the street. Let the mechanical governor do the work for you.

I'll tell you another old school trick. Instead of installing a shift kit you can take the valve body plate from a Cadillac or drill your existing plate to match the Caddy plate. Your transmission will work like a normal valve body plate until you kick it and then it works like a shift kit. No jerks when shifting while cruising only when you have it gagged.

 

Check vaccum modulator hose. B&M sells a governor calibration kit for TH350/700R4 which has different springs and weights pins and gasket. Simple to do but requires some time to fine tune and do. Adjust drive adjust drive adjust drive

 

Not only is the vacuum modulator suspect, but the modulator valve that is in the case must move freely. Vacuum must be present at the vacuum modulator at an idle, and if you disconnect it at the modulator, the engine idle should change.

 

Thanks for the tips i haven't hooked up the modulator yet so i'll get to that when i can.

 

That's your problem then. It needs to go to manifold vacuum.

 

Definately the issue... lol

The modulator controls the shift points based on manifold vacuume. High vac means the engine is under light/no load so shift points will be low, when their is low/no vac at all (which represents the engine @ WOT) the shift point will be alot higher!

 

You should have hooked that up prior to making this post?

 

Well being that this is the first time for me doing anything like this I think i deserve a little slack. I mean I did pretty well with the rest of it i built this motor MYSELF at age 17(just turned 18) and it runs excellently.

 

You deserve a pat on the back.