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Old 04-07-2011, 10:37 PM
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TCI constant pressure valve bodies

Been reading everything I can on the Constant Pressure Valve Body (CPVB) by TCI for the 700 trans and most of it is rather dated in the knowledge base. Has anyone installed one of these and had success with it? In other words have you the mileage on the trans. and if so, would you do it again? I know that there are conflicting ideas and opinions, but the proof is in the pudding. Installing the CPVB and running it for some time would certainly dispel/enhance some of these opinions. Any new and fresh ideas as to whether it still is/isn't a good idea? I'm torn between installing this in my trans which is behind a 327 with a mild cam and a slight overbore. I've heard so many stories about the trans being cooked because of the tv cable that I'm leaning toward the CPVB; but is it the right move?

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Old 04-08-2011, 06:15 AM
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i just set mine with the cable.
just over 3000 miles and still runs fine
the valve may be a good idea, but i dont know either ?
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Old 04-08-2011, 09:04 AM
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I believe using the TV cable gives the best performance from the tranny unless you have something going on that would require you to go to a CPVB. For your build, it sounds like there's no reason not to use the TV cable adjusted properly w/the correct geometry at the carb- although you didn't mention the induction system you're using.

There are recent threads here w/links to info on how to get the carb linkage set up right if you have a Holley, Eddy, Q-jet or EFI.
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Old 04-08-2011, 10:29 AM
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Cpvb

I'm either going to run the quadra-jet or an Edelbrock, although I don't like the smaller venturis of the Edelbrock. And then again there's the linkage set up for both carbs. Fun and games.
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Old 04-08-2011, 10:44 AM
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Setting the TV cable is no mystery. Read the available info on it and check out your options for bracketry, you do have options.

I use a Lokar bracket for my Holley setup and I love the adjustability of that thing! One little adjustment at the carb and my shift points go from "cruise the town" to "eat mustangs" in less than a minute.
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Old 04-08-2011, 01:02 PM
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I really would call the CPVB a constant pressure kit. It addresses and modifies a few areas of the transmission in order to achieve a constant line pressure. You can actually modify factory components and achieve the same results(if you can get a hold of the pr and boost valve).
That being said; I've installed a few of the constant pressure valve bodies from TCI with great results. The CPVB still uses the T.V. cable to determine the shift points only(not the line pressure like factory setup). The constant pressure feature actually comes from the different/modified pressure regulator and boost valve(necessary to keep line pressure down in reverse). The bias line valve is also blocked(search older threads for this modification on factory vb's). In addition to VB modifications and pressure valve modifications TCI also recommends the blocking of accumulators. TCI also uses a modified/calibrated seperator plate to achieve shift feel and timing.
This is important to note if the transmission has been internally modified for dual circuit feeding of the direct clutches(TH200 4r).DO NOT INSTALL THIS VB IF YOU HAVE INTERNALLY MODIFIED THE TRANSMISSION FOR DUAL CIRCUIT FEEDING(TH200 4r).
I actually have one of my 200's with a CPVB behind a 496 in a chevelle and it is holding up great. I actually recommended this install because the customer constantly complained about "shift firmness" with a modified factory vb. He would constantly adjust the T.V. cable and would ultimatley get upset with timing or firmness(this happend because he was adjusting incorrectly). We installed the CPVB and set the T.V. cable. He hasn't touched it since( we also had to modifiy the governor for a higher rpm shift). It has been thrashed on the stip weekly for two years. I should also note that I did modify the center support to dual feed the direct clutches with this setup. This can be accomplished by drilling an exhaust hole in TCI's seperator plate. PM me for instructions if anybody has questions or wants to see where to drill(once again this is for a 200 just putting the information out for other people).
I highly recommend a better band and an 093 servo with this installation. Just my two cents worth.

Good Luck.
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Old 04-09-2011, 07:39 PM
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Constant pressure valve body

As I understand it, it's possible to modify the valve body in a 700 trans so that it has constant pressure while the tv cable just controls the shifts. If so, is this a cheaper or better way to go?
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Old 04-09-2011, 09:20 PM
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To Modify or Not To Modify

Yes you could modify a 700r4 on your own if you had the experience/skill and the necessary parts. However, these parts are only easily acquired through TCI and therefore you are gonna end up paying more for the parts individually. I have bought a few replacment pieces when rebuilding/repairing CPVB transmissions and they are pricey. For example, the seperator plate is $45 approximately with shipping. IMO the TCI kit is fast, cheap, and has a great support system(phone and online).

However, there are modifications that can be done and yield similar results if you are willing to roll up your sleeves and get dirty. First, blocking the bias line valve. Second, replacement of the TV valve with a newer style(it has the multiple slots). Third, install sonnax booster valve kit 700R4-LB1. Or modify the VB and seperator plate to Loop TV supply oil(not easy/not for the rookie) Also, you could install a larger boost valve with a stiffer pressure regulator spring, but this yields harsh part throttle shifts.

Search Google for these modifications on bulletin boards and websites. If you want some more information I can supply some website addresses tomorrow.

Good Luck.

Last edited by ethn_bert; 04-09-2011 at 09:22 PM. Reason: forgot to mention TV modification for constant pressure
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Old 04-09-2011, 09:30 PM
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Cpvb

Thanks for the info. Will search for more info regarding modifications of the 700.
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