TH350 to 700R4

[big dump]

Thanks for the measurements RestoRod. I'll take a look today and see what I come up with. As far as a pressure gauge, I don't have one. I read on Bowtie Overdrive's site that you need a 0-300psi pressure gauge and a 90° 1/8"NPT fitting to hook up to the transmission for checking. They don't specify any type or brand of gauge, is there a generic one that can be used? I assume just some type of oil pressure gauge correct? I mean, it's measuring fluid pressure, not air pressure. Do you really think it's necessary to use up to 300psi?

[71RestoRod]

You might be able to use an oil pressure gauge for the off-idle test if you're careful. The line pressure on the low side is only about 10-20psi but if you rev it at all it will quickly build up to 100-200psi which would probably blow the fittings off of the gauge.

If you can swing it, take the time and find a 300psi gauge. It will probably come in handy diagnosing your problem. You might also call AAMCO or some local trans shop to see if they'll hook up a gauge and diagnose no charge.

[big dump]

Well, I broke down and took it into a shop here in Chandler that a guy that we pit for in Baja uses to tune his race truck. It's a bit pricey, but they do fantastic work, and aren't afraid to tackle a custom project. Link below:

http://www.adsautorepair.com/

I printed up a comprehensive list of everything that I've done, as well as a description of the problem that I was having, along with all the installation materials that I got from Painless, Bowtie Overdrives, Lokar, etc. on this project.

It turned out to be a vacuum delay sensor, which I KNOW that I DID read about in the installation of the TCC lockup from Painless (must have forgot and also convinced myself it was the TV cable). The last letter (G) in the instruction manual states:

G. IF YOU ENCOUNTER A CONSTANT LOCK-UNLOCK SITUATION IN CITY TRAFFIC
A VACUUM VALVE ( GM PART NUMBER 14020691 ) MAY BE INSTALLED IN THE
VACUUM SWITCH HOSE TO CORRECT THE PROBLEM.
NOTE:IF VALVE 14020691 IS USED BE SURE TO PUT THE BLUE SIDE
TOWARDS THE MANIFOLD VACUUM SOURCE.

As soon as they confirmed everything that I did in the install, and double checked the issues on the dyno, they ordered the part above from GM, and installed it for me. The install was free, the part was $35.00, but the diagnostic was a few hours at $96.00/hr.

One of those things that you kick yourself over because you know you could have figured it out, but just didn't. I'm glad to have it resolved, and it's running GREAT! I'll post an update soon to let you know it's still all good, along with some build pics of the whole conversion.

Thanks for all the help everyone.

[SeventyOne]

Very cool. I think I will take my truck in to a tranny shop once its together just for extra assurance.

[71RestoRod]

Congrats on finding the solution

[sakid]

Thanks for heading up this thread, it was exactly what I was looking for as far as info and the straight forward responses. Just a quick note on your high idle if you haven't already cured it. A lot of times with TBI units the gasket craps out on the mating surface to the intake. To find it, just spray some carb clean around the base where the TBI mates to the intake and if the engine bogs down or has idle fluctuation then you know that the gasket's failed. The part is only a few bucks and take about 20 min. to install.

[sakid]

Oh yah. Is a 2 wheel 700r4 longer than a 4x4 version? I think I remember reading something, but I wanted to confirm it. I'll keep looking.

[big dump]

Yes, SAKID a 2WD tailshaft is longer than the 4x4. The case is the same I believe, the tailshaft and housing are what's physically longer. Thanks for all the help guys, it seems to be running well and shifting good. I still kick myself for not recognizing the hunting gear issue because I definitely read about it in the Painless Lockup manual. Anyway, feel free to PM or post up with any questions as it's still fresh in my head for the most part.