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Discussion Starter #1
Currently working on sticking a 4BT into my old F-150 w/a C6 auto. I'm curious about the vacuum signal that goes to the carburetor. What do you recommend that I do with this? Can I cap it off or should I hook it up to a vacuum canister that'll run off the vacuum pump that's on my 4BT?

Are there any "side effects" to just plugging the line off or will my transmission prematurely implode?

Also, if you could, keep the anti C6 comments to yourself. Yeah I know a NV4500 will work better. I can't afford it and I'm stuck with what I have.

Any help will be appreciated. Thanks!
 

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You may also want to post your question to one of the other Ford diesel specific forums on the internet. What you will need to find is if the C6 was ever used behind a diesel in a highway vehicle. Three years ago there was an airport luggage tractor on EPay that had a 4BT & C6 combination. They did exist. I would imagine they used a fixed position modulator in place of the vacuum modulator similar to what was used in the 4BT with GM TH400/475 transmission. The only other option could be one of those variable vacuum regulators that is throttle position controlled that has been described in previous threads.

Keep us posted on your progress.
 

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I ordered a full manual valve body from BTE. I plan on just going full manual and leaving the vacuum line open to the atmosphere. Have been told by a few people that this has no drastic consequences.

Any C6 gurus out there have any input?
 

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I know this is after the fact, I do know that C6 transmissions were used behind 6.9 IDI engines with a vacuum controller on the Inj. pump, and I belive the alternator or the fuel lift pump had the vacuum pump. If you ever saw vacuum windshield wipers on the old cars you can guess what I mean.
My dad and I are looking into a Ford E150 4BT C6 swap to replace the thirsty 351W, we are in the "planning" stages. What I do know about C6 transmissions is, they have adjustable modulators, If you leave it open to atomsphere even with the manual valve body, it might have pretty harsh shifts. Adjusting the screw inside the vacuum nipple outward with a small standard screwdriver will produce softer/earlier shifts. and a person "might" be able to adjust it to a "happy meduim" where it will shift at a preset point all the time, It won't compensate for smashing it to the floor, or babying it up to speed. Also you might also have better luck with the downshift arm removed. I built a E150 w/351w C6 and removed the downshift arm because everytime I opened the 4bbl flusher, the darn thing would downshift putting my RPMs too high.

I have a question for you, what flexplate did you use? I know very little about the 4BT, I would guess it has a flywheel/starter attached to the block (like chevy V8) or the "big" diesels, and not to the tranny like (Ford).
 
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