I have a 400 transmission in my Chevy. The local transmission shop insalled a B&M shift kit. After the shift kit was installed, the transmission shifts too early with normal driving. The transmission shifts properly under heavier acceleration. I've tried to adjust the modulator valve, but it didn't help. I have also checked the vacuum to the modulator & it's okay. Could the B&M shift kit have caused this problem? I have also read that the double stripe modulator would help. Does anyone have the part # for the double striped modulator valve? Thanks.

 

What color is your modulator (stripes) now? Which way are you turning the screw to adjust it?

 

Modulator has single red stripe, I have turned it all the way in.