Trying to find information from anyone who has installed a 700R4 Transmission with the Holley 3x2 Tripower setup. I am looking for help on what brackets to use. Holley sells a kickdown bracket 20-121, but the throttle cable bracket 20-95 is not designed to work with the Holley 3x2. Bowtie transmissions only sell kits for the Rochester 3X2. So hoping someone has done this before. Thanks.

 

ou may have to check the AIM..

 

Turbo 350 and Turbo 400 are the standard Automatic transmissions for 68-80 corvettes. 700R4 was added in 1982. This would be a customer setup that I know has been done, but not in AIM as Holley TriPower and 700R4 were not introduced the same year.

 

But does the 700r4 use the same kick down setup that the 350/400 do or is it electronic....

 

Neither. The TH350 and TH400 used vacuum control, the 700R4 uses kick down brackets and is not electronic.

 

TH400 used an electric kick down switch.

 

I was looking on the AIM and it doesnt show any brackets either. You would have to make your own or modify the stock one with a down leg for the kickdown

 

Hi,
I'm just making sure you know that it's not a kick down function on the 700R4, rather it's the TV cable to adjust line pressure.. Can't help with the Tri-power setup but it sounds interesting..

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whats the line pressure do? Is it normally tied to the throttle on the carb?

 

I have a 700R4 tied to my 548 engine, but it is not a tri-power carb. Here, I have a single Holley 850 and use the TV cable for the kick down with a 4th gear lockout. I would imagine you are treading in new waters with the 3x2 set-up and a 700R4, but I am sure it will work with some ingenuity.

 

I never found anything that was made for my 700r4 TV cable. I used the stock GM cable and made my own bracket to hang off the carb intake manifold stud.

Just a little bending and welding and I had a local chrome shop make it look like a factory job

 

I was referring to the Holley Kickdown Throttle Bracket 20-121 that is required for the 700R4 hookup.

 

Did you do this setup on a tripower or single carb?

 

I'm no expert but I learned a lot getting mine right... Line pressure is how a trans knows when to shift and how hard the shifts are, low line pressure can result in soft shifts, slipping and what called stack shifts where it will shift from 2nd to third very fast for example. There are a ton of resources on the Web for how to adjust them but one should read a bunch because for stock OEM situations the adjustment is fairly simple. For non stock like the OP's you need to be pretty careful or trans damage can occur. There is a plunger in the trans that increases pressure, it should start to increase as soon as you press the throttle, and be bottomed out or fully on when you reach wide open throttle, I'll call that the Throw. To get the proper amount of throw the geometry of the throttle linkage needs to be correct, how far away the cable connection is from the pivot point of the carb throttle linkage.. to close=not enough throw, too far=too much. The cable mounting bracket needs to be far enough away to allow the cable to move the required amount.

In my case the PO went from a throttle body/Crossfire to a standard Holly and the TV cable bracket they made was to close, the geometry of the throttle linkage had too little throw, and to add to that, the throttle cable was wrong and it never made it to WOT. Add to all that was that it did not have a provision to lock the TC... I managed to save mine for awhile by getting the proper hardware from Bowtie Overdrive but I needed to get the TC changed for lockup so I had the Trans rebuilt and upgraded. I watched some of the work, he manually checked the throw with the pan off and adjusted the pressure with a gauge...His words "Get this wrong and let a 700 slip for any length of time and it's the beginning of the end"....

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700R4 have a TV cable aka Throttle valve cable , 700 transmission pump uses this information to determine how much pressure is needed for the function , light throttle pump backs off pressure for a smooth ride and relax the pump, full throttle it jacks up line pressure so clutches don't slip . Turbo 400/350 use the vacuum modulator to control pump pressure where 700's use a TV cable to control pressure ... 4L60 E don't use any cable or vacuum but a TPS sensor with computer to control pump pressure. TV cable un hooked will burn up a 700 quickly under full throttle

 

You need an adjustable cable with adjustable sheath along with cable and buy some after market brackets and cut weld and modify to fit ...
Will you be using a functional Lock Up unit or is this going to be a hydra-lock as soon as it gets in fourth gear deal or just bypass Lockup altogether with a Sonnex TCC by pass valve . TCC works with the cooler flow is why this is important , simply unhooking the TCC will restrict Cooler flow and burn up transmission eventually, slow death unless you go on a long trip

 

Like I said I COULD not FIND anything from anywhere that fit my 800 hp handling 700R . I had to make it. I had the 3800 stall 9.5 inch 5 clutch lockup . At certain point you have to just make it. I had a 26 vain pump and you have to set it or else your are going to smoke it.