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Loominnaughty

Putting a 4.0 inline 6 into a ‘86 XLS?

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Is it doable within reason?  Would I need to swap out the tranny too?  It’s a 5 speed manual.  New to the club!  Just bought my new toy, got a looooong way to go to get her perfect!  :)  Any advice is appreciated!

08B632F5-300F-4429-9367-32ADC77BFAF4.jpeg

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One of my friends who is on here has an 86 with a 96 4.0L in it. Most will say you had to modify the firewall to make it fit. On his I didn't see any modification to the firewall. But it is doable.

 

Looks like you got a really nice one. Do please post a build thread and post your VIN up in the registry and ill get you a build sheet.

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1 hour ago, eaglescout526 said:

One of my friends who is on here has an 86 with a 96 4.0L in it. Most will say you had to modify the firewall to make it fit. On his I didn't see any modification to the firewall. But it is doable.

 

Looks like you got a really nice one. Do please post a build thread and post your VIN up in the registry and ill get you a build sheet.

Done!

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early 86s will need the firewall mods.  late ones won't because they received the firewall for the upcoming 4.0.  we don't yet know the official cutoff though.  :dunno:

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Also, you would have to change the transmission, and the bellhusing, and very possibly the transfer case.

 

Tip: For an '86, the better swap is to a GM 3.4L V6 out of a rear-wheel drive car like a Camaro or Firebird. It's the same basic block as the 2.8L that Jeep used in 1986, but it's a much more refined and improved version of the engine. It'll produce more power, run smoother, and isn't likely to punch a connecting rod through the side of the block if you look at it corss-eyed.

 

The good thing about the 3.4L swap is that you get to keep your existing transmission, drive train, and accessories. You will need to add an external, electric fuel pump, but that's a worthwhile upgrade anyway. If you use the flywheel off the 2.8L, it has an eccentric weight because the 2.8L is externally balanced. The 3.4L doesn't need that eccentric weight, so you either use the 3.4L flywheel, or you have the 2.8L flywheel neutral balanced at an automotive machine shop.

 

 

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Thank you for the info!  Always looking for some wise tips!  I’m excited to bathe in your guys’ wealth of knowledge, can’t wait to get wrenching!

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6 hours ago, Loominnaughty said:

It’s also a 4x4 by the way.

 

What engine? I assumed it's a 2.8L V6, but it could be a 2.5L I4 (That's "eye-four," not "fourteen")

 

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No one else has mentioned it, so I will.

 

:soapbox:

 

The grill is upside down.  Please flip it over.

 

(I'm done.  Thank you.)

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6 hours ago, 87MJTIM said:

No one else has mentioned it, so I will.

 

:soapbox:

 

The grill is upside down.  Please flip it over.

 

(I'm done.  Thank you.)

Hahaha thank you!

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11 minutes ago, Loominnaughty said:

Hahaha thank you!

 

In case you misunderstood ... he's not joking. Your grille IS upside down.

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7 minutes ago, Eagle said:

 

In case you misunderstood ... he's not joking. Your grille IS upside down.

Yes I can see haha

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for a 4.0 swap you need the entire drivetrain, engine transmission and Tcase, and I'm guessing rear and front shafts... a 3.4 is a more straightforward upgrade... your call...

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1 hour ago, omega_rugal said:

for a 4.0 swap you need the entire drivetrain, engine transmission and Tcase, and I'm guessing rear and front shafts... a 3.4 is a more straightforward upgrade... your call...

 

For a 4.0L swap, you also need at least the complete engine room wiring harness, and the ECU (under the hood in a '91 or newer, under the dashboard 87-90). You also need the high pressure fuel pump.

 

For a 3.4L swap, there are multiple ways to go. You can leave everything as it is and run the 3.4L using the 2.8L ignition and carburetor (although it's a lousy carburetor); you can upgrade to a Weber carburetor setup; or you can grab the GM fuel injection for the 3.4L and run that as a stand-alone injection system.

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3 minutes ago, Eagle said:

you also need at least the complete engine room wiring harness, and the ECU (under the hood in a '91 or newer, under the dashboard 87-90). You also need the high pressure fuel pump.

 

 i forgot that, i consider that as part of the engine since it won´t run without it  :D 

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