Powerglide vacuum modulator

[Jeff S.]

Does the vacuum modulator and/or manifold vacuum signal (inches Hg) have any influence on the 1-2 upshift point at partial, very light throttle input? I'm experiencing a delayed & rather 'clunky' upshift under these conditions since moving from near sea level in Wisconsin to 7,500' msl in Colorado. The linkage is properly adjusted, moderate & full throttle upshifts as well as passing-gear kickdown operate as expected.

My manifold vacuum here is 13 to 13.5 range, compared to 19-20 near sea level. I'm wondering if it would be appropriate to try one of those 'adjustable' modulators. Can't seem to come up with any technical data to accurately describe just how -- or if -- modulator contributes to this situation.

Thanks in advance.

Jeff

[Edward J.]

Re: Powerglide vacuum modulator

Jeff, The kickdown is also throttle adjustment, tinker with the kick down adjustment to see if you can get to shift earlier. the later the linkage starts to push down the earlier the shift. If the adjustment does not seem to help maybe try the modulator with a adjustment screw.