I'm working on the shift performance on my 1987 300TD. I've gone through the vacuum system, replaced a few hoses where it was leaking and adjusted the modulator on the transmission itself. Overall the transmission is shifting well, however I think the output of the VCV is low.

Vacuum going into the VCV from pump is strong, around 25 inches. The VCV output measured at the line running to the BUFO is around 7 inches (measured at idle). The output from the BUFO to the transmission modulator is also around 7 inches.

I've done some reading on the VCV adjustment procedure (set throttle wide open, twist VCV clockwise until you feel resistance).

My question is regarding the ideal pressure coming off the VCV at idle? Based on my research I *think* it is around 12 inches at idle, but I'm hoping someone can confirm that for me.

Thanks