I have a 85 IROC, LB9 700R4, with less than 2,400 original miles. When accelerating normally (little old lady style), the tranny seems to be shifting through the gears all at once, causing the engine to lug. When I accelerate hard it doesn't do this. I've adjusted the TV cable and it made no difference. Anybody know what's happening here?

------------------
85 IROC-Z
2,3XX original miles

 

Sounds like the torque converter is locking up too soon, that is why it is lugging. With more throttle it goes away. You will have to install an aftermarket lockup delay to eliminate this. You will have to ask around on this.
Hope This Helps!!!

 

I can see how that could be part of the problem, but it is also shifting through the gears way too quickly. It's like bam-bam-bam and I'm in OD before the car moves fifty feet down the road. I can shift manually and avoid this problem, but I want to correct it ASAP.

------------------
85 IROC-Z
2,3XX original miles

 

Do you have lower than usual rear gears? That will tend to make the shifts happen sooner. Also, they earlier 700 shift timing left allot to be desired. Try This: To adjust the TV Cable skip the book method and do this: Press the D button on the adjuster and loosen the cable setting. Now, have someone floor the gas pedal while you check to see if the throttle plate is open all the way. Usually they are off a little and will wiggle. Do whatever you have to do to get it open solid. Now, with the pedal floored, press the D button and pull the cable back as hard as you can and release the button. You now have the engine, tranny and gas pedal all in sync at WOT. Mark the cable so if for some reason it gets moved you can know where to put it again. The problem with the 'self adjust method' is that it bends things and puts them permanently out of whack. It is also the full TV setting, which is theoretically what the GM method does. If that doesn't help and, as Pro Built mentioned, if the L/U isn't engaging too soon, then you will need to address the calibration of the tranny. I would get a TransGo Shift Kit. This, along with correcting the weak points in the tranny also corrects the early 700 shift timing problems.