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Bronco II 302 Swap Questions


Jaren831

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Just recently bought a pristinely maintained, bone-stock 1985 Bronco II (pictures below). Manual, 2.9 2.8. Want to turn this into a beast. 302 swap, suspension, all the bells and whistles. Want a overlanding/outdoor rig that I can also cruise around in. I've been scouring forums all over the internet and have the general idea of what to do, but I'm missing pieces and want to check with y'all. Never done something like this so want to check I'm getting my plans right.

Plans

Engine - Found 93 mustang fox body at junkyard, getting engine for $500. What's everything I need to grab from the mustang?
Transmission - Read stock transmission can't handle V8, need to upgrade. Upgrade with what exactly and what components? Can mustang transmission work, it's a T5?
Suspension - James Duff stage 3 lift, body lift. Read I need to upgrade axles. I've read front = dana 35, rear = 31-spline 8.8-inch axle. Are these both from an 90's explorer?

Wheels/bumper carrier/ other bells and whistles

What else am I missing? Videos seem to have a laundry list of upgrades.

Edit to answer some questions:

Will be keeping EFI.

00n0n_kVtKLvpSrOC_0CI0t2_600x450.jpg00g0g_hVyLC7VFjMZ_0CI0t2_600x450.jpg01111_5WUu7e5hjYh_0CI0t2_600x450 (1).jpg
 
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Rock Auto 5% Discount Code: F9A1A579ACFAD1: October 1st, 2021

franklin2

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Are you keeping the fuel injection? Or putting a carb on it?

If I were doing it, I would get a engine/transmission/transfer case from a f150 or full size Bronco. That way you would have all the drivetrain that matched the power output of the engine, and it would all bolt together with stock parts. You would then need custom driveshafts to the diffs. I have been reading that the trucks have a large bellhousing that doesn't fit very well, but since you are going to have a body lift that should not be a problem.
 

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You will want the FEAD components from a 5.0l Explorer. This keeps all the pulleys and things closer to the engine so you have room for radiator and fan.
 

85_Ranger4x4

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Explorer has the best of everything as far at the engine goes. Better heads, intake, FEAD, decent cam... all in one foul swoop. I would grab rear axle too. If the Explorer is new enough to have a V8 (96+) it is new enough to have factory disk brakes (95+) 91-94 Explorer for the front axle, the rear will work if you want rear drum brakes. 90-97 Rangers can have D35's as well but watch out for the hybrids, 95-97 Rangers have dual piston bolt on calipers.

Heat will be your enemy at low speed, get as big of a radiator as you can stuff in it.

For an overlanding rig (usually not crazy big tires) your 2.8 should suffice for a long while.

Your 2.8 (NOT a 2.9) is carbureted, for offroad/overland EFI would be ideal but you will have to convert it to EFI... so harness/computer and fuel system.

BEAUTIFUL Bronco II! :icon_thumby:
 
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Jaren831

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Explorer has the best of everything as far at the engine goes. Better heads, intake, FEAD, decent cam... all in one foul swoop. I would grab rear axle too. If the Explorer is new enough to have a V8 (96+) it is new enough to have factory disk brakes (95+) 91-94 Explorer for the front axle, the rear will work if you want rear drum brakes. 90-97 Rangers can have D35's as well but watch out for the hybrids, 95-97 Rangers have dual piston bolt on calipers.

Heat will be your enemy at low speed, get as big of a radiator as you can stuff in it.

For an overlanding rig (usually not crazy big tires) your 2.8 should suffice for a long while.

Your 2.8 (NOT a 2.9) is carbureted, for offroad/overland EFI would be ideal but you will have to convert it to EFI... so harness/computer and fuel system.

BEAUTIFUL Bronco II! :icon_thumby:
Thank you so much for your response. So getting the engine from the mustang is not worth it? If I grab from an explorer will I also need the transmission?

No matter what 302 I get it seems I have to replace transmission. Not sure exactly what type goes with whar 302 engine and fits in my bronco.
 

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M5OD R2 will have the SBF bolt pattern for the 302 if you want a manual. I believe there are others also. If you get the transmission along with the Explorer engine, you should have that covered.
 

Jaren831

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M5OD R2 will have the SBF bolt pattern for the 302 if you want a manual. I believe there are others also. If you get the transmission along with the Explorer engine, you should have that covered.
Ok so will be looking at 5.0l explorers for whole engine + computers etc, axles. I want to keep my bronco manual, do I need to find a manual explorer transmission or somewhere else? Not sure what M5OD R2 is in.

Also, exhaust upgrades would be necessary right?
 
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Jaren831

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Explorer has the best of everything as far at the engine goes. Better heads, intake, FEAD, decent cam... all in one foul swoop. I would grab rear axle too. If the Explorer is new enough to have a V8 (96+) it is new enough to have factory disk brakes (95+) 91-94 Explorer for the front axle, the rear will work if you want rear drum brakes. 90-97 Rangers can have D35's as well but watch out for the hybrids, 95-97 Rangers have dual piston bolt on calipers.

Heat will be your enemy at low speed, get as big of a radiator as you can stuff in it.

For an overlanding rig (usually not crazy big tires) your 2.8 should suffice for a long while.

Your 2.8 (NOT a 2.9) is carbureted, for offroad/overland EFI would be ideal but you will have to convert it to EFI... so harness/computer and fuel system.

BEAUTIFUL Bronco II! :icon_thumby:
My question then is about the transmission. My Bronco II is manual, want to keep it that way. I don't think explorer will donor trans right?
 

85_Ranger4x4

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Explorer would have the 4R70W. That is your automatic transmission option, its a good solid transmission if not horribly abused like any other automatic. I don't think they made manual V8 explorers.

M5ODR2 out of a F-150/Bronco is your best manual option if you want overdrive. Those out of a 97-04 F-150 with the 4.2 V6 has the shifter in the best location for an RBV. The 4.2 needs the bellhousing bolts opened up from 12mm bolts to 1/2" bolts. All can use RBV clutch hydraulics. You will need to have a tune made if you are using the Explorer computer or any computer for an automatic AFAIK, my truck is carburated so that was a non issue. You may have to deal with PATS too. Ranger M5ODR1 shift lever can be adapted to fit. I used a '96 F-150 clutch kit, you will need the engine separator plate from a 5.0 '150 too (you can carefully enlarge the starter hole with a dremel in an automatic plate but it is a PITA)

Mustang vs Explorer is complicated.

V8 Mustangs are kind of scarce in yards around me, what ones do make it to a JY are very sketchy. Explorers are everywhere, it would be pretty easy to cherrypick a nice one that hasn't been totally ran thru the wringer.

It is a PITA to pull the FEAD out of an Explorer, the radiator/condenser has to come out. You have to drop the oil pan to get the timing cover off. And at the end of the day it is a better engine (Most foxbodies did have forged pistons... they are 30+ years old now though) Explorer has the closest to the engine belt system Ford ever designed, a 130a alternator that is easy to replace and a good power steering pump. The intake is a cast version of the GT-40 intake they made for Mustang Cobras.

You will need the dual sump pan and pickup from a foxbody though. Get a new pickup whatever you do, I snagged a pan off craigslist for like $20. There is a special main cap bolt that has a stud made into that holds the pickup too.

2C33E3BE-3C4F-450B-95AB-1D7DB48C45BE.jpeg
 

MikeG

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I don't think that the v8 explorers ever came with a manual trans..... if they did, good luck finding one.

Edit - looks like I was hitting 'send' at the same time as the post above......
 
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Craig_S

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I'm doing the exact same build as you now. My B2 is stripped and I bought a complete 97 Explorer to plunder.

No offense meant at all, but if someone doesn't know the differences between a Fox Mustang 5 liter and an Explorer 5 liter, they need to do some reading. Short version is you want both. But how do you have both engines at the same time? Ok here goes. The mustang will have a better stock cam (which required and included better valve springs) and better pistons. The pistons are not a huge deal for what we're going to do, but it's a difference so I mentioned it. As mentioned above, the Explorer has better heads and upper/lower intake. The cam isn't as powerful (so the valve springs are pretty weany) but again for our purpose it's fine. Try to take advantage of the better top end in the Explorer engine with a cam means you gotta install matching valve springs. Back in the day I remember reading that even a stock Mustang cam would overpower the Explorer valve springs. As mentioned above also, you want the front brackets, ps pump, and ps reservoir from the Explorer. Basically if you have to pick between the two engines you want an Explorer. Then we get into electrics. The Explorer has what I'd call an overly complicated, all encompassing system that does not lead itself to easy mods. It also has a funky distributor less ignition. So you want the mustang versions of the computer and distributor. Confused yet? Yeah, FoMoCo screwed the pooch by not giving us GT40 goodies in the Mustangs, and when they put it in the Explorer they did it again by changing stuff that didn't need changed.

Personally I bought a complete 302 from a 90 GT. I got it in 1994 with 4000 miles on it for my 64 Fairlane but my plans changed and its been on a stand ever since. I'd like to use this engine because it's basically new, but the Explorer engine is tempting too. No idea what I'll do yet although I will have to use the combination I previously talked about.

Several guys use a standalone computer system called microsquirt and it looks nice. I'll probably go that way.

Now for the transmission, a lot of guys use older C4's. Why? Because they don't need computers. The 4r70w from the Explorer is great because it has overdrive.... but it's computer controlled. Manual valve body? Yep, perfect solution but that will cost a LOT too. This is a sticking point which I didn't decide on yet either. No point in using my 4r70w transmission with 200k+ without rebuilding - that's a huge bill too.

Rear end, definitely go Explorer. Just choose the brakes you want and go from there.

Some advice for the Explorer - I found one that was high mileage but perfectly maintained. It was CHEAP, and I mean CHEAP. And I'll never do that again either. Why? Because 1) it was at a friend's place a little over 3 hours away, so there's a day of my life I won't get back, 2) it literally took forever to get it apart because of some rusty crusty stuff and how they crammed everything in there, and 3) now what's left of this thing is in my way. I think it would be better to pay upwards of $1000 for the separate piece needed for the build and have the time and space for other stuff. Yes I almost got the Explorer FREE and I don't think I'd do it again. Just something to consider.

Want some good inspiration and help with info/build tips? Look up "Sarge GPW302B2" and "Randum Adventures" on YouTube. Hard to find the second ones channel name with a search but if you search Bronco ll V8 or Bronco ll 5.0 you'll find both of them easily.

I'll stop here because I'm trying to type this all on my phone. If you want to talk more that's cool. I'm glad someone else is pretty much where I am. Let us know what you decide on the engines.

Craig in PA
88 B2 EB
89 B2 XLT
 
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85_Ranger4x4

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Explorers are also OBDII which is more advanced than the OBDI Mustang.

Unless somebody does the work for you both engines are a mild PITA to pull. Both could be in a JY so no biggie on disposal. The last 5.0 Mustang I saw in a yard (two years ago) was extremely rotted and actually almost folded in half from a very hard hit on the front. Water pump was broke and most of the engine was in the passenger compartment. They don't grow on trees.

I had a C5/4, the mileage sucked. Like 10-12 mpg cruising at 2700 rpm. Also kind of a PITA to convert to 4wd (I had the tailhousing from a RBV C5) The gas pedal was about a quarter inch from getting into the secondaries at cruise... so the primaries were about wide open. I swapped in a M5ODR2 which is also what the OP wants to do. My well used Crown Vic shortblock with a HO cam, E7 heads and a 4bbl gets 18mpg in a lifted brick with a highrise topper. Zero regrets on the transmission choice.

I pulled the FEAD out of an Explorer for mine, I think it is about half the work of pulling the whole engine. Big PITA but however you want to cut it the accessories are VERY worth it.

Here is the writeup on how to install and make it work in an older truck from when I installed mine:

 

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Great info there @85_Ranger4x4 and thanks for the link. Is there a special wrench I should get to remove the Explorer fan? I pulled the engine complete from upper intake to pan and fan to flex plate. I'd like to get the FEAD off to do cleaning and maintenance before deciding which 5.0 I'm going to go with for my build.

Craig
 

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Craig_S

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My craftsman wrenches are awful thick and at the moment I can't remember if it was the Bronco or the Explorer that had very little clearance to get to the nut. Made me think somebody probably made a thin special wrench to get in to snag that sucker.
 


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