I am currently restoring a 1973 GTO. Back in 1973 I had a friend who had a 1973 Trans Am that had an in car adjustable modulator valve. It was mounted under the dash and he would turn the knob left or right to determine shifts points. It had a Bird on the knob which looked like O.E. but he might have glued that on there. I was wandering if anyone has ever seen these? I have looked all over the internet with no luck.I thought it would be cool to have one of these in my GTO although it really has little purpose. Any help would be appreciated,Tim
Almost all the replacement modulator valves available now are adjustable via a small flat blade screwdriver inside the vacuum nipple. Maybe your buddy had a cheater valve like on an air tool spliced into the line or something like that. Going from one end of the adjustment to the other is hardly perceptible while driving, the adjustment isn't good for a whole lot of change. Its a fine-tuning feature.
+1 matt. that would be my guess also.
76 455/4spd TRANS AM69 GRAND PRIX 455/5SPD