Dec 27th, 99, 09:14 AM
I have just installed a new TH 350 in my 67 to replace a powerglide. However, the TH 350 will up shift at around 2,500 RPM. Does anybody know of a way to make it shift a little later so I can take advantage of the top end horsepower.
Dec 27th, 99, 09:35 AM
Hey rick look on the passenger side of the tranny. Look for a vacuum line running to the modulator valve. Undo it and see if there is a little screw in there thay will except a small flat head screwdriver, if not get one. Turn the little adjusting screw in clockwise. The more you turn it the harder and later your shifts will be. Expect to be down there a couple of times ( trial and error)
Dec 27th, 99, 11:14 AM
interesting, does the th400 have the same style screw?
Dec 27th, 99, 12:36 PM
I never heard of that one,Jokerdwarf,do you know what this is actually adjusting?I would like to try that myself.Also,Rick,did you adjust your downshift cable properly?It also effects your upshift points.I learned the hard way,I just did this swap this past summer.The downshift cable should be fully extended at W.O.T.,a little bit of adjustment made a big difference on mine.
Dec 27th, 99, 12:42 PM
Hey guys. The modulator valve adjustment is pritty simple. By turning that screw in or out its regulating how much vacuum it takes to shift. Remember turning it in will make the shifts delay longer resulting in a firmer shift.....try it....if yours is not the adjustable type, you can buy one from even autozone like three dollars. only one bolt holds it on....good luck let me know what happens firstname.lastname@example.org
Dec 27th, 99, 12:45 PM
Oh yeah I forgot. In answer to the question regarding the th400. I don't think they operate the same way. I could be wrong though. Also you guys are right the detent cable does also affect your shift points. I currently have a goofy metric and it completely shifts off of the cable. I pulled it off and the thing would never shift into second or third.....funny
Dec 27th, 99, 04:47 PM
Joker, Thanks for the info, I'll try it as soon as I get it running again. I'm in the middle of a disk brake conversion right now.
Dec 27th, 99, 05:38 PM
The turbo 400's also have the adjustment
screw. It is on the outer side of the modulator.
I would only adjust a little at a time, it will get to a point where they will not shift
up at all.
Just my 2 cents.
Jan 2nd, 00, 09:38 AM
Thanks for the help. It took two full turns to raise the shift point by 1000 RPM. When I started it would shift at 3000 RPM with WOT. Now it revs to 4000 RPM with WOT. I might still take it up a bit but 4000 seems to work pretty well. Thanks again