700r4 TV cable adjustment check

[Gene King]

Hello. I put a new carb on recently, got the proper mounting and geometry bracket and I'm setting the TV cable. I watched a decent amount of videos but I'd hate to burn up my trans so I thought I'd ask, I've got it set so that max throw of the TV cable is set to maximum throttle which seems like the general consensus but then at an idle it's kinda loose. By feel this edelbrock 1405 has more throw in the throttle than the qjet that came off, my pinhead can't compute if that factors into this but it concerned me. I took it for quick spin and it went into 2nd at 10mph and 3rd at 20mph. Am I good or did I goof it? Thanks appreciate the help

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[Matt69olds]

Ideally, you would want to install a pressure gauge on the trans. The textbook spec is 90psi at minimum throttle, and should start to rise at the slightest increase in throttle. Max line pressure will probably be 240-275ish depending on what boost valve is in the pump.

Did you floor the throttle under the hood, or in the cab? Make sure the throttle goes WOT with your foot on the pedal, if not, make sure the floor mats aren’t keeping the pedal up, or the linkage isn’t flexing, or some other reason the carb isn’t opening all the way.

Your 1-2 shift sound a little on the low side, but may be acceptable depending on what valve body calibration your trans has. Obviously a valve body from a Camaro will have a higher shift point than one from grandpa Cadillac. If it has a solid thud shift, with no mushy slip/sliding feel, and the shift points are consistent and repeatable, your probably ok.

Just to cover your ass, you might want to discuss your concerns with whoever built the trans.

 

[Gene King]

Thanks for the advice. I've got a redneck operation here, no pressure gauge and GM built the transmission 35 years ago heh. I think I've got it pretty dang close after some adjustment, I drove a 700r4 in a Camaro for near a decade now and just went down the road a bit in the truck pulling over and adjusting it until it felt the same, which put it just a little tighter than what I have in the video. I couldn't do a side by side of the tightness because this is actually the carb from that car on the truck. Thanks again

 

[Sublime]

Thanks for the advice. I've got a redneck operation here, no pressure gauge and GM built the transmission 35 years ago heh. I think I've got it pretty dang close after some adjustment, I drove a 700r4 in a Camaro for near a decade now and just went down the road a bit in the truck pulling over and adjusting it until it felt the same, which put it just a little tighter than what I have in the video. I couldn't do a side by side of the tightness because this is actually the carb from that car on the truck. Thanks again

So what MPH is the 1st to second shift at now? I read somewhere that 17 mph is a good indicator. Im learning myself as I just acquired a K5 with this transmission and know nothing about it.

 

[Matt69olds]

If the transmission is the original to the truck, snd it’s never been rebuilt, then I would guess the shift points should be pretty close to whatever the factory manual outlines. Maybe someone in readerland has a book that could post the typical shift points?

If you have had the truck for a long time, how do the shift points feel with the nee carb verses the original? If they are noticeably lower than before, the cable isn’t right. Within reason, too much TV is preferable. You won’t burn up a transmission from the pressure being to high, biggest drawback is the hard shifts. Run the trans with the pressure low, and a couple mushy shifts is all it will take to glaze the clutches. Once that happens it’s all downhill from there.

 

[Gene King]

@Sublime I don't feel comfortable recommending you numbers with how janky my adjustment procedure was and how uneducated I am about them lol. This other Matt seems like the guy to ask
@Matt69olds It is original to the truck but the truck is new to me. I did keep in mind that preference for tightness, I started it too tight in hindsight and it revved high in 1st without shifting 'cause it thought I was deep in the gas, so I knew she was too tight then, pulled over and adjusted it back from there slowly until it felt just on the tight side of perfect 'cause I'm a chicken.

 

[Matt69olds]

This is a article I found that might help.

https://gearsmagazine.com/magazine/a-look-back-adjusting-the-thm700-r4-throttle-valve-cable/

And this one.


http://www.superchevy.com/how-to/83878-automatics-throttle-valve-tuning

 

[Gene King]

Good stuff thanks. To be honest if I knew it was going to be all this stressing to get the trans adjusted right when I started this project I would have tried a lot harder to fix it's q-jet, that's my word of advice to people reading this later lol. At least if you're a regular joe trying to get the truck to run right like me.

 

[Matt69olds]

Agreed. It’s hard to beat a well built Q-Jet. Unfortunately, after 25-30 years of use, you can’t fix the wear and tear with a 30 dollar rebuild kit from AutoZone.

As long as it shifts with a solid thud, chances are you will be fine. If in doubt, run it with the cable a couple clicks too tight. Shifts that are a little delayed to too firm are much cheaper than the other way!