Engine problems/swap ideas 1981 4x4 custom bronco

[bigben81bronco4x4]

Bully, I hate to keep rambling on however Im not sold on doing a rebuild yet....Here is where Im at and why im not sold on it. We had it running....Decent....Before changing the muffler I took it on a main 4way to see if I could stretch her out a bit. I couldnt keep it at 60 and could hardly get it above 60 in third gear and dont bother going from 3rd to overdrive. No power hardly at all. even the slightest incline would cause you to have to downshift to maintain speed. I know it never got over 62 or 63. The truck does not smoke at all. It does have a tick on the top end which I think is a valve needing adjusting. Im still considering the off dp intake a 4bbl card set up to get a little top end power and wake it up a little. We changed the muffler as well. After changing the muffler and adjusting the timing ( it wasnt off but very littel ) it runs but it stalls heavily on take off. Im no motor guy or mechanic but I just want to explore options before sinking a ton of money into a rebuild. At least with the carb and intake upgrades if I do them I can reuse them if I do end up having to rebuild....Thanks for your help....

 

[bigben81bronco4x4]

Really want suggestions on what the reason for the power loss at 50 plus mph

 

[JLasvegas]

plugged up cat?

 

[bigben81bronco4x4]

No cat on it...Sorry

 

[Bully Bob]

Well.., this has gone somewhat "full circle".

Maybe best to start at the begining with all the tests/checks.

M5 has all the check lists but a book would help you as well. I don't think I mentioned a compression test & timing chain test, as well as the aforementioned. (plugs, points, wires, module, electronics, computer, etc.)

Something makes me think the the guts of the eng. are OK..! You likely have more than one "tune" issue.

That engine should pull most any hill with ease.

IMHO, intake & 4 brl carb. isn't going help at this point & could just amplify the problem. However there could still be a problem in the current carb.

Like JLV said.., it could be something as simple as a cat converter.., but not in your case.

I'm not up on exhausts but having the "cat" missing may cause issues..??

BTW.., what is the mileage on the clock..?

 

[miesk5]

yo BEN,

Since you are not the owner that bought the Bronco New in 81, I am wondering about what you wrote; "going from 3rd to overdrive..."

I am GUESSING that a prev owner or shop swapped the AS BUILT 1981 C6 trans that does not have OD (three speed non-electronic)

to an AOD or E4OD, etc. that does have OD

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AOD Pan has 14 bolts





If the shifter has a P-R-N-OD-D-1 pattern, the transmission must be an AOD

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C6 ID;

Pan has 17 bolts "Utah" shape



If it is the C6; one simple check is the Vacuum Modulator; You have a Vacuum Modulator on the rear of the transmission. Pull the vacuum line off the mod. If fluid comes out of the vacuum line the Vacuum Modulator diaphragm is damaged & trans fluid is getting by.

or vacuum line is cracked or disconnected on engine side.

The Vacuum Modulator adjusts the shift points (tells the tranny when its okay to shift). http://web.archive.org/web/20080224083518im_/http://danielphotography.us/bronco/c6modulator/modulatorc6.jpg

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E4OP Pan: 20 bolts

has an Overdrive Cancel Switch and a P-R-N-OD-2-1 shifter pattern

Let us know what you have in there.

 

[bigben81bronco4x4]

miesk5, Im not real sure....I can get under it tomorrow afternoon and let you know. Its a manual with reverse top left the first, second, third and overdrive at the bottom right. Is your asking suggesting there could be a trans issue? Thanks again for every ones suggestions and help.