1977 F150 w/a Cummins. Have a transmission question (C6)

[Clayslayer]

(moved this thread here)

Hey all,

Have a question, tried the search but came up dry. C6 doesen't have three or more characters. Wasn't sure where to put this cause it's a little different but here it goes anyway.

I am putting a Cummins 4BT into my old '77 F-150. I have a C6 automatic. Previous engine was a 429. I'm using an adaptor kit from fordcummins dot com out of Montana. So far so good.

Anyone have any recommendations on what to do with the vacuum signal? What I'm planning on doing is going to a full manual valve body (from BTE), thus eliminating the need for a vacuum signal for shift points and leaving the vacuum modulator on the transmission there with the line open to the atmosphere giving it the impression of WOT all the time (no vacuum) rather than try to rig up some contraption or other.

Is there any negative consequence to doing this? There aren't a whole lot of options out there for what I'm doing. I've checked all over the net, and over at 4btswaps dot com and nobody seems to have a clue.

Any input from a knowledgable C6 guy would be appreciated. Thanks!

[M.L.S.C.]

It was my understanding that the full-manual valve bodies run full line pressure all the time to begin with, so I see no adverse effects to doing what you are planning on. However, what I would suggest is calling the manufacturer of the manual valve body and asking them the same question, and let them recommend a solution.

[Clayslayer]

Agreed. I've done that already and they don't really want to make any comments concerning durability. A full manual valve body is not typically used in a "street" application, and more for drag racing use where longivity is not really all that important.

I have talked to another fella who has already done the same thing I have and has put 10,000 miles on his rig with no issues but I plan on driving mine much more than that if at all possible.

[M.L.S.C.]

Regardless of durability, what line pressure settings do they recommend for the manual valvebody? If they can't come up with a number (say 100 psi at 800 rpms) you ain't talking to the right folks, and you may wanna look elsewhere for a VB source...