I plan to do an LT1 swap for my thirdgen but the only engine I can find is a complete dropout with a 6 speed tranny. That means the PCM is also for an M6. I plan on reusing my 700R4 from my 91 RS. Will that be possible or do I have to get a new PCM? The 700R4's aren't electronically controlled. Thanks.

 

The only problem you will have is that the speedo will not read correctly without reprogramming the PCM. Since you will need programming anyway, to correct for tire size if nothing else, it shouldn't be a problem.

Rich Krause

 

Um...Your PCM controls your lockup (TCC) in your 700. You can work around this, but you'll have to know what you're doing. There's some "Creative Wiring" involved. And NO, you can't run a 700 without lockup on the street.

Frank
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I don't think this is the whole answer at all, though I am not a tranny guy. First of all, you can simply use a non lock-up converter. If you want it to lock up, there are two choices. One is simply to convert to a manual lock up switch. Here's some info on how to do that http://www.smokemup.com/tech/700r4.php.

Here's some instructions on how to hook up a lock up switch that works on a pressure switch: http://www.73-87.com/garage/lockup.htm

No matter what, I would advise against trying to make the PCM control it. I thought the question was "would the PCM work" and figured the original poster knew about the lock up issues.

Rich Krause

 

Putting a toggle in a car for TCC function is a real pain in the a$$! Who wants to toggle it on and off everytime?
And....As I stated! You cannot use a non lockup converter in a 700 on the street! It'll overheat the transmission. Anything with an O/D needs lockup to keep the transmission cooler.

To hook up lockup CORRECTLY without PCM control, you'll need a brakelight switch to take the conv. out of lockup when you hit the brake. You'll need a low vacuum switch to take it out of lockup when you mash the throttle (passing gear). You don't want the conv. locked when you try to pass someone. You'll need either a 3rd or 4th pressure switch in the valvebody (late 700's don't have provisions for a 3rd switch) to keep lockup out until that specific gear.
Unfortunately, late 700's don't even have a lockup control valve in the valvebody.....BECAUSE the PCM contolled it. Earlier units had a valve that we could adjust the spring pressure in to tailor the lockup apply timing. This is one of the reasons I like to use early 700's (with late updates) in non-pcm equipped vehicles (Street Rods, Etc.)

Frank
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