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4.0 into 84 Bronco II


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I got started on the engine swap this weekend and figured I'd start a thread on it. First, a little history...

We've owned this Bronco II for a couple of years now, and it has earned the name "Little Brown Deuce." When we first got it we couldn't drive it faster than 35mph and keep it between the lines. We ended up replacing the suspension system and several steering components, and finally got it to where we could drive it pretty comfortably at 55mph. That is, when it was running.

The previous owner rebuilt the 2.8L, and I have no doubt he did a good job overall, but it's been one problem after another. Even on it's best day, the 2.8L has been really unimpressive in the power category.

More recently, a nut from the air cleaner stem fell into the carb, through the intake, and found it's resting place on the #4 piston. At least, I'm pretty sure that's what happened. Either way, it smoked the intake valve and seat, smashed the piston, sticking the rings. Rather than putting time and money to get back to a running motor I didn't really like in the first place, I figured it was time for an upgrade.

I've seriously considered a 302 swap, but finally decided to pull the trigger on buying a 92 Explorer with the 4.0L. So I plan to swap the motor, the center console, maybe front seats, and eventually the axles.

The donor is a 1992 Explorer 2 door. Motor is good, auto transmission is bad. Overall seems to be a pretty sound vehicle.

The recipient is a 1984 Bronco II, which is currently waiting for a heart transplant to mount back up to the 5 spd manual transmission. We installed a 4" lift, sat it on 32" BFG's, and regeared to 4.56 gears.
20220513_081036.jpg


I've swapped Chevy 350 motors in and out of a few trucks, but haven't taken on a swap like this before. I'm pretty comfortable with the mechanics of it, but the wiring seems intimidating. Lots to learn...

This weekend I started stripping the wiring and accessories from the 4.0, labeling all the wires as I disconnected them. I've been going slow and trying to enjoy the process, and taken pictures along the way to help when my memory fails.

I also have some young men that I'm hoping to bring along in this project, and leverage it as a mentoring opportunity. Depending on their availability, I'm hoping to pull the motor after work this week and get it on a stand and stripped down. Not planning to rebuild it, but throw a gasket kit at it and check the timing chain. I'll do more if needed, but I'm hoping more won't be needed.

Resized_20231022_150641~2.jpeg


More to come.
 


gaz

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4WD
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Ranger 5sp, BII A4LD
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Ranger 33"/4:10LS, BII 29"/3:73LS
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Deengineer until it is how Blue Oval should have sold it!!
@Bronson with Bronco ,
Since you are already installing a gasket kit and timing set, I urge you to consider having a performance valve job performed with new valve guides and stem seals (inspect the push rods/rockers for servicabiy, they are not adjustable and are known high wear items). A new oil pump/pick-up and water pump are also a prudent move.
 
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@gaz
Thanks for that. I was planning on inspecting the pushrods and rockers, as I understand those to be high wear items. Sorry for the ignorance, but what do you define as a performance valve job on this engine? Also, do you recommend a particular oil pump?
 

Shran

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Start there, I did a similar swap. Really depends on if you want to use your dash or the Explorer dash. Significant pros & cons to both. Explorer harness is easier to use an a Bronco II than a Ranger harness because of things like rear wiper, defrost, etc. You will need to also do something with the fuel tank, sending unit, fuel pump situation.
 
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@Shran
Thanks. I plan to keep the original dash. I don't have a rear wiper or defrost, so hoping that should make things a little easier.
 

gaz

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2WD / 4WD
4WD
Total Lift
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Total Drop
Ranger 5sp, BII A4LD
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Ranger 33"/4:10LS, BII 29"/3:73LS
My credo
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@Bronson with Bronco ,
FOR ANY ENGINE, NOT JUST FORD 2.9L
There are several terms that get thrown around when discussing valve jobs. If you ask an experienced machinist for a performance valve job, the machinist will probably ask you about the expected END RESULT level of performance.

Instead of asking for a 3 angle, 5 angle...blah-blah-blah, I have learned that if my machinist understands my expectations, then I can trust their experience, since they are the authority on how to achieve it.

The terms I will use with the machinist are:
• performance, valves and fresh ground valve seats, new valve guides/seals, resulting in improved flow over stock
• race, improved flow beyond performance level
• full race, the wicked end, no greater improvement in flow possible.

I believe Mr Sven Pruett recommend using either a Melling (M128) or a Melling (M328) high volume oil pump. I used the high volume pump in my 1st 2.9l build but later learned:
1) the high volume pump steals or uses approximately 7% more power from the engine.
2) match the input/output orifices (Mr Pruett's book)
3) use the standard pump but disassemble it, deburr where necessary and polish where it improves performance. This doesn't present increased load on the engine in fact just the opposite. When done in conjunction with improved oil passage and improved top end oiling work...it is superior.

NOTE
- The Melling high and standard level oil pumps use different pick-ups.
- I have never needed any better flow from stock valves than a performance valve job offers.
* SPECIAL NOTE, while I have yet to see one of these Ford 60°v6's with over 100k miles on the heads not benefit from a performance valve job, I have also not seen a set of "RECONDITIONED", like new or new Heads not benefit from the same process!!
 
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@gaz
Thanks for the detailed answer. That's very helpful.

I've been reading through Pruett's book. Spent time last evening reading on cylinder heads and valves.
 
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4.0 is coming out tomorrow after work. A couple high school boys are coming over to learn, and I've got the old 2.8 on the stand that we can tear down easily and talk about the different parts and their purpose.
 

bobbywalter

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Should be a breeze.... disconnect the bullet connector at the firewall. Power the diode in the power distribution box. Jump the starter relay.

It should run.

Break your wiring down from there.
 
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Got the 4.0 out of the Explorer last week. The high school boys seemed to enjoy the time and learn a few things. My wife and I went to her parent's place a few hours away for the weekend to put up some firewood for them, so finally back to the project this evening.

Not a lot accomplished this evening, but I did pull the valve covers, intake manifold, and rocker assembly. I wanted to get a look into the motor, and also inspect the pushrods. I think I'm the first one to open this motor up, and everything is looking pretty good (to my mostly untrained eye). However, one pushrod has me wondering. Of the 12 of them, 11 look identical in terms of wear. One of them, however, has worn differently on the rocker end. You can see the difference on both the rocker and the pushrod in the attached photo. The right is a smaller dark spot than the left one, and the left one is typical of the other 11. Is this from poor oiling on this one, or from this one receiving better oiling? What's the remedy? Blow compressed air through the oil passages? The pushrod in question is the #5 exhaust. And, at what point do the pushrods need to be replaced? And do pushrods necessitate new lifters and rockers? I'm wanting to spend my pennies wisely on this project.
IMG_20231113_190253716_HDR.jpg
 
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Spoke to a friend about my pushrod question, and he said it wasn't anything to be alarmed about. I'll check the oil passages in the rocker assembly before buttoning it all back up.

Last night I installed a new Cloyes 9-4172S timing chain set and Melling M128 oil pump. The bottom of the oil pan didn't have any chunks or shavings, and VERY little sludge, so I'm happy with that. Waiting on a Fel Pro gasket kit to be delivered next week, then I'll get the motor put all back together. I've also ordered a new Luk flywheel (LFW156) and clutch kit (Luk 07-096).

In the meantime I'll clean up the valve covers and maybe throw a little paint at them, and work on getting the rest of the wiring out of the Explorer.

The wheels are also starting to turn about the fuel system. Anybody know if @DieHardFord is still around here? He did this swap on an 85 Bronco II and has this article -
I've emailed him, but received no reply.
 
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Got the rest of the wiring out of the Explorer, as well as the fuel system (lines, tank, wiring). Spent the afternoon cleaning up valve covers, timing cover, and oil pan. Gasket kit arrived in the mail, so engine should get buttoned up this weekend.

That said, I should be yanking the Explorer out of the garage in the next day or so, and getting ready to roll the Bronco in.
 

gaz

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87Ranger Endrigo 2.9l, 87BII Endrigo 4.0l
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4WD
Total Lift
Ranger 5" (1.5" suspension), BII 4" suspension
Total Drop
Ranger 5sp, BII A4LD
Tire Size
Ranger 33"/4:10LS, BII 29"/3:73LS
My credo
Deengineer until it is how Blue Oval should have sold it!!
@Bronson with Bronco ,
My current fuel system solution (87BII w 94 Explorer 4.0l) is to use either an 89 or 90 BII fuel pump/sender unit with the rest of 4.0l Explorer's, as they use the same set up as the 4.0 (idea credit goes to @Shran ).
 
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@Bronson with Bronco ,
My current fuel system solution (87BII w 94 Explorer 4.0l) is to use either an 89 or 90 BII fuel pump/sender unit with the rest of 4.0l Explorer's, as they use the same set up as the 4.0 (idea credit goes to @Shran ).
I'm pretty sure that, in addition to what you've done, I'll also need a fuel tank from an efi Bronco II. Do you have plans to change your current fuel system solution?
 

gaz

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Make / Model
Ford
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87Ranger Endrigo 2.9l, 87BII Endrigo 4.0l
2WD / 4WD
4WD
Total Lift
Ranger 5" (1.5" suspension), BII 4" suspension
Total Drop
Ranger 5sp, BII A4LD
Tire Size
Ranger 33"/4:10LS, BII 29"/3:73LS
My credo
Deengineer until it is how Blue Oval should have sold it!!
@Bronson with Bronco ,
The complete fuel system is:
87 BII chasis
87 BII fuel tank
89 BII fuel pump/sender
94 Explorer fuel lines
94 Explorer fuel filter
94 Explorer fuel rail+ injectors

To the best of my knowledge, the fuel tanks in BII remained unchanged throughout production, 23 gallon behind the rear axle. I'm using an 89 fuel pump/sender unit as it drops right in the stock fuel tank and is the updated hi pressure in tank pump, just like used in the 94 Explorer's system.

The only reason that I'm not using the Explorer's fuel pump/sender is that the pick up tube and level gauge aren't designed for the entry angle (30° surface angle) and do not hang deep enough (the Explorer sender sits level on top and the tank is not as deep).
 

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