General Category > Quadrajet Carb Talk and Tips
th350 detent valve travel question
tayto:
Too bad delco doesn't make one. I found this:
https://www.classicindustries.com/shop/1979/pontiac/firebird/parts/transmission/automatic-trans/shift-linkage/
similar to what you have already? you can get small nico press crimps for small "aircraft" cable that should would, ive used them to shorten throttle cables. i think i got them from home depot or acklands grainger up here in canada. see attached image. have you tried setting the cable tighter? I've always set the tv cables ao cable is tight @ wot, never had any luck with the auto adjuster.
stevef:
--- Quote from: Cliff Ruggles on March 14, 2019, 04:59:13 AM ---For most set-ups and my own car I don't use the transmission kick-down feature. The last thing I want to happen is the transmission seeking a lower gear during a heavy throttle passing scenario. I'd rather manually shift it if/when needed....but my engine does make over 550hp and 600ft lbs torque, so it really doesn't need high RPM's for any sort of "normal" driving........Cliff
--- End quote ---
I've noticed you've said that before. Since I probably only have around 200 hp and 320 ft/lb torque, AND only 2.41 rear gears, a kick-down is very desirable :) .
stevef:
--- Quote from: tayto on March 14, 2019, 08:09:11 AM ---Too bad delco doesn't make one. I found this:
https://www.classicindustries.com/shop/1979/pontiac/firebird/parts/transmission/automatic-trans/shift-linkage/
similar to what you have already? you can get small nico press crimps for small "aircraft" cable that should would, ive used them to shorten throttle cables. i think i got them from home depot or acklands grainger up here in canada. see attached image. have you tried setting the cable tighter? I've always set the tv cables ao cable is tight @ wot, never had any luck with the auto adjuster.
--- End quote ---
That is the type of cable, but that one is for Chevy small blocks. Each make of engine uses a different length cable, so the Olds uses a different one. But, I figured out how to solve my problem. My solution is written in the next post.
stevef:
So, I figured out how to fix my situation. I re-installed my new cable and took another look at how it was actuating the detent valve in the valve body of the transmission. As I mentioned earlier, when I adjusted it by the book, the valve still had about 3/16" travel left at full throttle, when the valve really needed to be close to fully depressed, and that's how it still was. So, I tried an experiment. Instead of opening the throttle lever on the carb wide open before locking the snap-lock button on the cable for adjustment, as is the factory procedure, I unlocked the cable and rotated the throttle lever only about 3/4 wide open before locking the snap-lock button the cable. Then I opened the throttle to wide open and checked the valve again to see how that affected the valve travel. Now it was fully depressed! This in effect made the cable adjustment shorter, so when it goes to full throttle, it pulls the cable a little further than before and the kick-down valve becomes fully depressed. I also checked it to make sure the valve was being depressed sufficiently by using the gas pedal, and it was (thanks "tayto"). So, I test drove it and it shifted fine and I have a reliable kick-down function now. I just drove it on a 40 mile round trip to a friend's house this evening with no problem. I still don't know why it's not adjusting correctly by the factory method, but I'm glad I found a fairly easy way to make it work. It takes a little trial and error adjusting it this way, but it only took me 2 tries. Now that I know what's supposed to happen, in the future, I'm going check the detent valve actuation in any th350's I use before putting them in use.
Thank you both for responding!
tayto:
Like I said the factory method for setting the TV cable on the 700R4/2004R has never worked for me. This is most likely due to the shift kits installed and how they "fix" the TV system with spacers and stiffer springs etc (my theory anyway...). Glad you figured it out and verified your gas pedal!
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