Thread: Adjusting shift points on 1985 turbo 350 automatic

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I have been told that the shift points on an older (1985) turbo 350 automatic transmision can be adjusted by turning a screw inside the modulator valve clockwise, 1/4 turn at a time untill it shifts at the proper time. I have used the 305 engine and turbo 350 transmission out of a heavy car (4-door Pontiac Bonneville) in my model A roadster pickup which is quite light, and now when I stand on the pedal (hard acceleration) ot even in normal driving, the car only moves about 15 to 20 feet before it shifts from low to second. The shift from second to third happens at a more "usual" time/RPM range.
I would like to know more about this.--Where inside the modulator valve is this screw? is it on the side that the vacuum line ataches to, or on the side that screws into the transmission? If I take the modulator valve off the tranny, will my transmission fluid run out the hole ,or is the modulator valve above the fluid level? Does this adjustment only adjust the shift point between low and second, or does it also have an effect on the shift point between second and third? I would like to adjust this shift point, but don't want to have to drain the fluid, drop the pan, and incurr the associated costs at a transmission shop.
If anyone has some good solid information on this, please let me know.
I do not want to put in a shift kit at this time, as I am looking for a low budget way to do it in my garage without having to take much apart, and without going to a transmission shop $$$$$$.
-----Brian