[ChevLoRay]

I had an old-skool drag racer who has been building automatic tranny's for years, to modify my valve body for firmer shifts. It was a simple matter, involving drilling one hole, blocking another, and reinstalling it with a new modulator...specifically a smaller one. It is black, and apparently, the color of the modulator has something to do with the operating characteristics of the modulator.

In my case, he said there wasn't enough vacuum signal to operate the larger modulator for kickdowns, etc. I don't currently have a kickdown hooked up, but it will kick down into second, from drive, if I floor it. It speeds up very good and shifts firmly, but not hard enough to bark the tires. If I floor it hard enough, and the speed is right, it'll kick down to a lower gear. I think I might get better gas mileage, if I had the electric kickdown working. I bought the Lokar unit, but I think adding a button under the gas pedal might just work. Oh, I guess I'd need a gas pedal, so scratch that. Right now, all I have is the arm that the pedal contacts....one of the ball studs broke off and I haven't replaced it.

I know that this doesn't answer your question, but it offers a different view on the topic. I suspect that the problem may be in the shift kit/valve body, but could also involve the modulator, if the cam doesn't generate the vacuum needed for proper operation of the gearbox. It sucks to spend good money on something, only to have it not work like you expected it to work.

Was the tranny bad before you had it modified, or was it operating properly and you just wanted a shift kit installed? One more suggestion: Contact the manufacturer of the shift kit, explaing what you told the board, and see what their tech people say.