On a 350 Turbo transmission, turning the modulator valve screw
clockwise will generally make it shift quicker under low vacuum conditions. This is because it increases the line pressure. However, it's crucial to understand that this is a *very* sensitive adjustment. Small changes can make a big difference, and turning it too far can cause harsh shifts or even damage the transmission.
Important Note: Before making any adjustments, it's strongly recommended to find a qualified transmission mechanic. Incorrect adjustment can lead to significant transmission problems. This adjustment isn't a simple fix and is usually best left to professionals.
