Alum. Powerglide Question

[OldCarPilot]

Its looking like the vaccum diaphram on the tranny is screwed up. Car runs like shit at idle in gear with the vaccum line hooked up, and runs ok with it off. I left it off and ran the car and the shift points are exactly the same as when I have the vaccum line hooked up. I'm guessing it doesn't work and hasn't since I've had the car. (only about a month) Is leaving the vaccum line off of the tranny for a while going to do it any harm?

[gettingreasy]

I never had the vac. line hooked to my PG the entire time i drove it(about 10 months), before I replaced the engine/tranny. I could really feel the difference when I plugedit off, shifted real crisp andat a highe RPM then before, as far as I could tell it never hurt it but then again I used to do Neutral drops from reverse down to low at 30 MPH and it never hurt that damn glide.
-Jesse

[CTFuzz]

I had a 283 with P/G in an old Ford truck, ran it without vacuum line for six years, then sold it to a friend. He drove it 5 more years before replacing it with a 350/350.
I really like the way the P/G shifted!

CT.

[OldCarPilot]

Those are the answers I was looking for!

Thanks

[Flatdog]

The vacum modulator on an Aluminum powerglide controls pressure inside the transmission, not shift point. The shirt points are controlled by the throttle rod going up to the carb. Leaving the vacum modulator line off will make the trans think that it's at wide open throttle and raise the pressure. It was a trick years ago to help out a worn out trans. Your motor running worse with the vacum modulator hooked up sounds like you might have a modulator with a ruptured diaphram that leaks oil.