fade380

I put a rebuilt th350 on my 88 monte carlo ss and it will not shift. It just stay in high gear. I was told to put a vacuum line from the carb to the trans. I did and still no shift. The TV cable that run from the trans to the carb has a little slack in it but it is on the carb. When I pull the TV cable, I can feel it move like it is suppose to. Why will it not shift. I have a Mega Shifter B&M shifter on it. I need to ride man????: help!!!

Z28/2002

iTrader: (27)

modulator valve bad?

Gilbert@Ace Racing

There is an issue inside the tranmission itself. What can you tell me about the build itself?

The vacuum modulator may need to be adjusted, but I doubt that's the issue if it's a fresh rebuild

g

RPM WS6

iTrader: (3)

Did you connect the vacuum line to a full manifold vacuum source? Make sure that you did.

There is no TV cable on a TH350. It is a detent cable, and it has absolutely zero effect on light/part throttle shifting (unlike the TV cable on a 700R4 or 200-4R). That detent cable is supposed to have some slack when the throttle cable is at idle, so this is not your issue. The only effect that this cable has on shifting is that it will force a downshift at WOT to a lower gear (if vehicle speed allows) and extend the automatic WOT upshift rpm to a higher rpm. You could completely disconnect it (mine is) and the trans should still shift normally under any sort of cruising conditions, though it might shift a bit early at WOT.