FMX Vacuum Modulator Adjust

[mach1dave]

Guys, I can't remember if you screw the little adjustment screw in the vacuum inlet, on the modulator, in or out to make my FMX box shift slightly later?
Thanks.

 

[Gregaust]

Screw in for later ..

 

[mrgmhale]

If screwing the adjusting screw does not get you where you want in upshift points, you can change the length of the modulator rod, where a longer rod will increase the speed of the vehicle before the upshift occurs. Ford used to sell different length rods, but I used to fabricate them from round metal stock, and used a grinding wheel to round off the ends instead of them being square cut so they would fit better into their respective sockets at both ends. There is very little pressure applied to the rod, so you can use a softer, easier to cut/grind metal like copper. I think I used the none flux end of used welding rod back in the day.

 

[Bentworker]

Some more info here. https://7173mustangs.com/threads/fmx-valve-body-info.39371/