I have an 88 F350 7.3 with a C6 and since I bought it it won't shift right. Its like it just waits way to long to shift. It wont shift into third until you hit 50 mph. How do you adjust when it shifts? Is it even possible?

 

On the injection pump on the drivers side that black thing sticking up with the vacuum hoses on it is the vacuum control for the modulator in the trany. With out knowing the specs or procedure (someone will post them soon enough) you can loosen the two screws and rotate the controller one way, drive it then the other way and drive it and you should be able to zero it in. It will also have a kickdown linkage on the same side, make sure it is not binding anywhere. good luck

 

How to adjust VRV by James a friend on mine.....

You don't have the engine running for the test, you need to apply 20" vacuum (Hg) to upper VRV port and attach vacuum gauge to lower VRV port. The lower port is the one that goes to tranny, the upper to vacuum pump.
You have to maintain 20" vacuum (Hg) througout this test. If it drops off you need to pump it back up.
Remove throttle return spring, cycle throttle lever 5 times from idle to WOT. Make sure 20" vacuum is maintained on upper port side.
Move throttle so it is 0.515" (33/64") from wide open (they make a tool for this). Vacuum gauge should read from 6-8" of vacuum (Hg). If incorrect adjust VRV to 7".
Again apply 20" vacuum, cycle throttle from idle to WOT 5 times. Return to idle. Gauge should read at least 13".

It says if you can't get the 7" or the 13" to replace the VRV. If VRV checks out maybe the diaphragm (modulator), line from VRV goes to the vacuum diaphragm I believe. Can't find any adjustment for the diaphragm but I think there is a little.

Basically all you need for the test is a vacuum pump (handheld type), vacuum gauge and a ruler to measure 1/2" or a 33/64" drill bit in lieu of the .515" tool. And a screwdriver for any adjustment needed.
Good Luck
James

Note..... 20" vacuum Hg is equal to MINUS 65 Kpa..........

Check the vacuum canister for holes on the bottom.......

New canister......
http://store.summitracing.com/partde...5&autoview=sku

 

I rotated it like farmnfly said and it works much better. Thanks guys.

 

Sorry for reviving this old thread.

What should the vacuum input to the VRV be? I'm getting 30 in HG. Is that too high?