Air pressure isn't the big player it's the additional throttle angle applies at high altitude for "normal" driving. At lower altitude the engine makes more power everyplace, so less throttle angle to drive around, and higher vacuum at the same time. Since the modulator is a load sensing device, it shifts later/firmer with more throttle angle and lower engine vacuum produced by that deal.
So if one were to adjust the modulator for desired shifts at 5000', for example, and you took the car down to sea level, it will shift earlier and just a tad "softer" in the "normal" driving range......Cliff
__________________
If you can read this, thank a teacher. If you can read this in English, thank a Veteran!
https://cliffshighperformance.com/
73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile),
|