Engine swap

[mj86]

I have a 86 with a 2.5 and want to put a inline 6 in it. Made the purchace of the 6, it came with harness and computer. Any tips and help with this would be much appreciated. I believe it has a a904. Ive heard i will need to move a motor mount and possibly mod the firewall ?

My name is Sid Carlisle from flint mi. If u can help ill get u my #

Thanks for any help

[Jeep Driver]

I need the engine mount brackets off your 2.5, will you sell them to me?

[cody.quattlebaum.16]

I need the engine mount brackets off your 2.5, will you sell them to me?

I am doing the exact same swap, if he doesn't want to sell just brackets then I will. Let me know if yall don't make a deal.

[Pete M]

I have a 86 with a 2.5 and want to put a inline 6 in it. Made the purchase of the 6, it came with harness and computer. Any tips and help with this would be much appreciated. I believe it has a a904. Ive heard i will need to move a motor mount and possibly mod the firewall ?

My name is Sid Carlisle from flint mi. If u can help ill get u my #

Thanks for any help

 

 

the 2.5L's transmission won't bolt up to a 4.0L. 

[Dillithium]

I haven't done it either, though it is in my future(hah).

The 86 doesn't readily accept a 4.0, since it wasn't in circulation for the MJ at that point in time.

 

You'll need to modify the radiator support on the top for the new 4.0 radiator(much bigger), massage the firewall backwards to accommodate the head, find a transmission to bolt up to the 4.0(ax15/aw4) and weld new motor mounts in. Don't forget a new transmission crossmember, that may need to be drilled and tapped into the frame rails.

 

Also, what is your axle and tire setup like? If you're still on factory tire size with the 4.10 gearing, the drive will be...exciting.

[mj86]

I have and a904 trans and was told the 4.0 would bolt up to it. My front is a d30 and rear a d35 with 4.10. i currently have a 4" lift with 31" tires

[mjeff87]

I haven't done it either, though it is in my future(hah).

The 86 doesn't readily accept a 4.0, since it wasn't in circulation for the MJ at that point in time.

 

You'll need to modify the radiator support on the top for the new 4.0 radiator(much bigger), massage the firewall backwards to accommodate the head, find a transmission to bolt up to the 4.0(ax15/aw4) and weld new motor mounts in. Don't forget a new transmission crossmember, that may need to be drilled and tapped into the frame rails.

 

Also, what is your axle and tire setup like? If you're still on factory tire size with the 4.10 gearing, the drive will be...exciting.

 

Agree on everything except the welding of the motor mount brackets.....no welding, those bolt to the framerails.  2.5 brackets look almost identical to 4.0 ones, but trust me they are different.  You'll need the 4.0 brackets, and can reuse the 2.5 mounting hardware, but will have to align them with different holes in the rails.

[Dillithium]

 

I haven't done it either, though it is in my future(hah).

The 86 doesn't readily accept a 4.0, since it wasn't in circulation for the MJ at that point in time.

 

You'll need to modify the radiator support on the top for the new 4.0 radiator(much bigger), massage the firewall backwards to accommodate the head, find a transmission to bolt up to the 4.0(ax15/aw4) and weld new motor mounts in. Don't forget a new transmission crossmember, that may need to be drilled and tapped into the frame rails.

 

Also, what is your axle and tire setup like? If you're still on factory tire size with the 4.10 gearing, the drive will be...exciting.

 

Agree on everything except the welding of the motor mount brackets.....no welding, those bolt to the framerails.  2.5 brackets look almost identical to 4.0 ones, but trust me they are different.  You'll need the 4.0 brackets, and can reuse the 2.5 mounting hardware, but will have to align them with different holes in the rails.

 

 

Huh, I didn't know that. Thanks for correcting me, that makes it even more attractive to do!  :)

[Jeepman]

I have done this swap for a customer and did not have to Massage the Firewall at all, yes the core support had to modded to fit the 4.0L radiator and the mounts as mentioned are a bolt in swap... 

[mjeff87]

Dillithium......:cheers:

 

and on the same topic, you need 4.0 motor mounts as well.  2.5 ones look the same, but are not.

 

You'll also need a new throttle cable and most likely a gas pedal from a 4.0L MJ/XJ too.

 

It's the little things on the  2.5/4.0 swap that kill you.....you don't think about them until you run into an old part that doesn't play well with the new stuff, and it's late at night, the junkyard is closed. :fs1:

[mnkyboy]

Haven't really messed with the A904, but your current engine uses a 60 degree GM bolt pattern and the 4.0l uses the AMC V8 pattern so the engine is not going to bolt up to it.

 

Not sure what it would take to put them together.

[Pete M]

what did the a904 come from?  for that matter, what did the 4.0 come from?  are they both from a wrangler?  I don't believe the 904 has an overdrive.

[Incommando]

Yep. The 904 is an old Mopar 3 speed automatic

[Stacks]

I have an A999 (beefed up A904) behind my 4.0 in my MJ.  Bolts right up.  Only issue was the starter. Had to use a starter for a 258 with auto to get the engagement right for the starter and flexplate.  Normal 4.0 starter doesn't reach the flexplate.  I would recommend using the HO style throttle linkage/cable.  The one with the bracket for the throttle cable that attaches to the intake in the center front to back next to the valve cover.  That makes it much easier to get your kick down linkage working right and have some adjustment etc.  :)

[mj86]

Thats what i have 3 speed auto, original trans.

[nitroxsteve]

Thats what i have 3 speed auto, original trans.

I don't think you can use the trans that is currently behind the 2.5 with a 4.0

[Jeep Driver]

I looked at a 84XJ couple of years ago for sale, seller would not come down in price for me........but.......

 

It had the carbed 2.5 with the 904 trans........so.........

 

What's everyone talking about here? what am I missing?

 

Here-

 

DJ-5L (1982): GM Iron Duke engine 151 cu in (2.5 L) straight-4, Chrysler 904 transmission  http://en.wikipedia.org/wiki/Jeep_DJ

[nitroxsteve]

Correct me if I'm wrong but the 2.5 and 2.8 share the same bell housing bolt pattern. I think the OP wants to use the transmission from his 2.5 and bolt it to a 4.0. Or am I reading it all wrong?