My trans shifts fine NA (or so it seems) from 2nd to 3rd. Tried the nitrous for the first time Sunday and it would not shift from 2nd to 3rd until I backed off the gas pedal for a second. I'm going to set the nitrous shut off point on the 685 ign. box a couple of hundred rpm lower than the shift point to help this. But is there any other easy thing to do, to help the 2-3 shift, in case it is getting weak? Thanks for any help, Rick.

 

Barring that the 3-4 clutch is going bad. The most likley reason has to do with tuning and the time allowed for the shift. First the time it takes for the trans to make a shift at WOT is a fixed value. Now what this means is it takes lets say .2 seconds to make the shift, of during the shift the rpm is rising . Now lets say N/A it take 200 rpm to make the shift(this number could be more or less) But with NOS the rpm rise by 400 rpm in the same time period. Now lets say your shift it set at 5800 rpm and your rev limiter at 6000 Now NA the shift would have time to take place before hitting the limiter. However on NOS the RPM would have exceeded the rev limiter before the shift could be completed hence you bounce the limiter.
Best fixes lower the WOT shift point to allow time with NOS
Use a window switch during the shift but still you may need to lower the shift point some but not as much because though the NOS is killed again it takes the engine a moment to respond.

 

It did feel like it might have hit the limiter. Thanks for the info. Rick