I just recently rebuilt my 69 big block Corvette engine for the 3rd time. This time I put in a cam that produces less vacuum (I can tell by the headlight actuators), but more horsepower. I'm really happy with the engine this time, but the 400 trans feels totally different now. The shifts are real soft and it shifts from 1 to 2 and 2 to 3 too quickly. It used to wind out in first when I punched it and chrip the tires as it hit second, especially in the 2nd gear setting. Now the only way I can get it to wind up in first is to hit my kickdown switch, and even then, the shift is soft and the tires rarely chirp going into 2nd. Can the vacuum modulator be the culprit, or is it my new torque convertor, or a combination? It used to shift hard and now it doesn't even feel like the same trans. Any ideas? Thanks