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2.5l to 4.0 swap info needed?


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Since your is an '86 your not going to get a 4.0L into it without modifications to the firewall.

I did this conversion and had to do nothing to the firewall. Had to completely replace the header panel and radiator support, trim the area behind the headlights and replace the hood. Had to move the cross member back and shorten the drive shaft. You must have a complete parts vehicle to do this. I used a 94 xj. Not to complicated just time consuming. Motor mounts just bolt in in place of the 2.5l ones. You cannot use you exist tranny go for an aw4 if auto or ax15 if a manual. If you have any more questions just ask.

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Ok call me stupid than, cause I tried to put the 4.0L into my '86 MJ and I needed a good 2-3" more clearance at the firewall for it to fit. Ended up ditching that project and put a 3.4L in instead. And trust me I know my way around doing engine swaps as I work for a world known engine tuner/builder.

 

What exactly are you guys doing to get it to fit in?

 

I know they changed the firewalls in '87, wonder if your guy's were late '86 builds where the firewall already changed?

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hey I'm new to jeeps and I'm purchasing an 87 with a 2.5 and a 4spd on the floor next week and I'm wondoring EXACTLY what needs to be done to put in a 4.0. ive done engine swaps in chevys but its a little diff obviously and I'm wondoring if what components i can use that are stock. id like to keep the 4sp cause it has 4.10s and i plan on eventually running 35's (yes i know the axles won't last long) is is possible do i have to modify the tcase in anyway?

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hey I'm new to jeeps and I'm purchasing an 87 with a 2.5 and a 4spd on the floor next week and I'm wondoring EXACTLY what needs to be done to put in a 4.0. ive done engine swaps in chevys but its a little diff obviously and I'm wondoring if what components i can use that are stock. id like to keep the 4sp cause it has 4.10s and i plan on eventually running 35's (yes i know the axles won't last long) is is possible do i have to modify the tcase in anyway?

 

you can't keep the 4 speed. it won't bolt up to the 4.0

 

you need a donor vehicle, it's header panel so you can fit the 4.0 engine in, and all the wiring for the 4.0. that's inside and out of the cab. then drop the 4.0 and the entire 4.0 drivetrain in the truck.

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no tcase problems? would an 94 xj work?

 

94xj would work. you need to use the t-case FROM the 4.0 so that will throw out the np205 you have...

 

the 94 is a High output so you're makin a good bargain on power with that swap :D only thing you will need to have custom made may be the rear driveshaft...but you can probably find one or yours may work. I'm not sure how different the tranny lengths are.

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welcome.

 

don't forget you need the shift linkages for the np231 t-case from that 94 xj, you will have to pull the dash out to swap that wiring, and splice the rear tail lights back into the xj interior wiring.

 

and you'd need to lay the 4.0 wiring down in the engine compartment before putting the engine in.

 

it's not as hard as it sounds...it will require some drilling/welding on the header panel to put the 4.0 one in, but then after a few beers the rest of the project goes pretty smoothly...not a 1 weekend project, but can be done in a few weekends.

 

 

you will also need either an inline fuel pump that puts out the correct psi for the HO 4.0 or you will need a tank off a 91 or 92 comanche (those wer high output) and the sending unit for that...the 2.5 one won't work and the cherokee one doesn't fit.

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almost seems not worth it. me and a professional mechanic would take how many full days you htink? (i am pretty good with stuff like this)

 

I've never done that swap so I can't say.

 

I can tell you it took me approximately 16 days to stuff a camaro 3800 engine in my comanche with little help from others...and that included custom exhaust, motor mounts, AND putting in a 4.0 radiator and lower support.

 

you're not customizing anything. so I'd say less than 2 weeks of full days. I'd say a good 4 weekends at most plus one for troubleshooting.

 

trust me, it's worth it.

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Yes, put a 4.0 HO into a 89. The key is to have all the parts that you need when you start and have some help. If you can have 2 helpers is a lot better. One can pull everything out inside while two pulls the 2.5 and drive train. Also helps to have the right tools jamminz.gif

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dirve train as in the whole sha-bang (axles tcase tranny) or just tranny and engine

 

you don't need to swap axles.

 

you need the ENTIRE xj chassis so that you can yank things and literally lay them directly into the comanche chassis...otherwise you'd have a mess of parts and you won't know where to put them.

 

a first time swapper should pobably not just acquire all the parts seperately...which you technically could do...but buy a cherokee that runs and drives and has the parts you need.

 

better yet if the cherokee is a collision or rust bucket...then you don't feel half as bad.

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