nurkvinny Posted May 3, 2004 Report Share Posted May 3, 2004 The S-10's tranny started doing dome weird shit yesterday. It's a TH350, stock guts, ~3000 rpm converter, medium-size cooler. Until yesterday, you could hold 1st to any RPM you wanted, same goes for 2nd and 3rd. Now, under medium accelleration with the shifter in 1st, the tranny will shift up into 2nd for a few seconds, and then shift back into 1st on it's own. It does this with the shifter never leaving 1st. Also, about every third time you run the gears out, near the top end of 3rd, the thing feels like it hits neutral out of nowhere. Fluid is full and clean, lines are tight. I called Jegs; they have a TCI short-tail TH350 sitting on their shelves that I can have installed by Norwalk. I was just hoping that someone has ran across this before and could shed some light on the cause. Quote Link to comment Share on other sites More sharing options...
desperado Posted May 3, 2004 Report Share Posted May 3, 2004 combination modulator bad/going bad and your kickdown is stuck. Either that, or the mechanical govoner froze up. Anything else that would do that is valve body problems. If you have not put a shift kit in it. I would say that it's got real problems if none of the stuff I mentioned above are causeing it. If you have had the valve body down, there is a good change that something came loose/gasket blew between passages. Quote Link to comment Share on other sites More sharing options...
nurkvinny Posted May 3, 2004 Author Report Share Posted May 3, 2004 I'm with ya on the first part, but I don't have the kickdown hooked up. Quote Link to comment Share on other sites More sharing options...
desperado Posted May 3, 2004 Report Share Posted May 3, 2004 Did it flop back then somehow, or is it tied off good. Better check it. After reading post again. I need to check my manuals at home to give a better diagnosis. But as a guess, I would say that the pressure is dropping in 3 near the top and it is goig into netural. The other I am not sure on but I will check. Quote Link to comment Share on other sites More sharing options...
nurkvinny Posted May 3, 2004 Author Report Share Posted May 3, 2004 STOP EDITING YOUR POSTS AFTER I REPLY . The cable is tied off securely, but you got me thinking about the fact that the cable may be extended. This engine may also have a very different vacuum supply to the modulator than the other engine. Wonder if trying a different carb port fro the vacuum line to the mod would help any? Quote Link to comment Share on other sites More sharing options...
desperado Posted May 3, 2004 Report Share Posted May 3, 2004 I was editing my post while you were replying. The vacuum supply to the modulator should be from the manifold vacuum. On a holley, that is the one on the baseplate, front of the carb, pointing to the right front. If that don't get it, swap it to the brake vacuum port of the manifold. If you have it on the right side of the front bowel then you have two problems, one is that it's the wrong port for the modulator, second is that you have the vacuum advance connected wrong as well. That is the port on the metering (jet) plate on the front of the carb, over the passenger idle mixture screw. Hoping that it is a holley, if not this is more typing than I needed to do. Quote Link to comment Share on other sites More sharing options...
nurkvinny Posted May 3, 2004 Author Report Share Posted May 3, 2004 It's a Holley 750 Vac Sec. The advance is on the correct port, and the modulator is on the same port as I had it on the other engine, the one you describe above(although it was a 650 Holley). I'm gonna install a B&M adjustable modulator tonight and double check the vacuum and fluid lines, as well as check the position of the kickdown cable where I have it tied off. If all this fails, I'll relieve the 15+ year old tranny of its duties and take a late trip to Jegs. Quote Link to comment Share on other sites More sharing options...
AngryBMW Posted May 3, 2004 Report Share Posted May 3, 2004 LOL Vince, I cant wait to see this best run. -Marc Quote Link to comment Share on other sites More sharing options...
nurkvinny Posted May 3, 2004 Author Report Share Posted May 3, 2004 Originally posted by MadMalibu: LOL Vince, I cant wait to see this best run. -MarcNothing exciting about a 14 second truck. Quote Link to comment Share on other sites More sharing options...
desperado Posted May 3, 2004 Report Share Posted May 3, 2004 Speaking of which, when are you gonna get a big motor in that thing? Quote Link to comment Share on other sites More sharing options...
AngryBMW Posted May 3, 2004 Report Share Posted May 3, 2004 Originally posted by Desperado: Speaking of which, when are you gonna get a big motor in that thing? Who me? You have a donor(read: free) motor I can use?? -Marc Quote Link to comment Share on other sites More sharing options...
desperado Posted May 3, 2004 Report Share Posted May 3, 2004 No, I meant Vince. I thought he had a 4.3 in that. Of course I could be wrong. Quote Link to comment Share on other sites More sharing options...
nurkvinny Posted May 3, 2004 Author Report Share Posted May 3, 2004 Originally posted by Desperado: No, I meant Vince. I thought he had a 4.3 in that. Of course I could be wrong.I'm toying with the idea of going slightly larger than a 4.3 I went to Main St Jegs and bought a vacuum modulator on the way home. Didn't need it. Found that I did accidently switch the advance and modulator lines. Damned thing runs 150% better. Good to go for Norwalk. Quote Link to comment Share on other sites More sharing options...
desperado Posted May 4, 2004 Report Share Posted May 4, 2004 See, the Great and Powerful Desperado knows all! Visions of performance parts plague his mind constantly! Good to hear that you got it squared away Vince. Have fun at Norwalk. Quote Link to comment Share on other sites More sharing options...
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