C4 cruise-o-matic

[Rev]

I think you are referring to the adjustment screw on the vacuum modulator. It will allow earlier or later upshifts at part throttle. The upshifts at wide open throttle are determined by the governor which is an internal device and is not readily adjustable. The governor is set for the torque curve of the stock engine and so shifts at 4500 or so.You may be able to get it to shift automaticly even up to 5000. That's where I have mine and it's the highest I can get. If you need to shift at higher RPM's than that, you'll need to do so manually or else have some internal modification done to the governor in the tranny. I just do the "shuffle" as I have for a good many years now. It's not really very difficult once you get used to it.

Rev