help 86 MJ SBC Swap - Help?

[PlntXprss]

Let me preface this with some backstory,

 

I picked up an '86 i4, 2wd MJ for $400. It's rough, missing the bed, exhaust is all but gone, floorboards are shot, etc. I have no sentiment towards this Jeep, so I have no problem cutting it up to make this work. Furthermore, I have an opportunity to pickup an ENTIRE power-train (read: motor, trans, xfer) out of a 1980 K10 for FREE + shipping/gas to drive and get it. Were it not for these facts, I would not be even considering this project.

 

Now that that's out of the way...

 

As someone who has never swapped a motor before, what are some things I may not even think to research? How much cutting and firewall massaging am I looking forward to? Will it fit in my engine bay? (I think this is the short '86 that won't fit a 4.0). What are my options for motor/trans mounts? I'm sure there is a lot that goes into this that I haven't even considered, Who has pointers?

 

And yes, I've used the search feature of not just this forum, but Google as well - I've bookmarked dozens of pages for this project.

[Green Mesa XJ]

Something quick would be a 3.4 v6, essentially a 2.8 v6 the other option for your engine bay. There is a thread here (I believe it is) where somebody has a few gm v6 swaps written up.

A small block v8 is not out of the question either. But the v6 3.4 from a 93-95 Camaro will bolt up to you current transmission.


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[Jeep Driver]

 

 

I'll be doing this same swap myself in the near future. 

 

It's the only repower that makes sense. Frankly, it's the only power that makes sense. 

[ftpiercecracker1]

Disclaimer: I have never put a sbc into an mj.

 

BUT, I have read countless threads regarding the operation and have a j10 that does have a sbc/t400 in it. Currently working on it too.

 

 

Easiest path forward with least amount of work, which will still be a lot of work.

 

No gauges.

Manual choke

mechanical fuel pump

Power to distributor 

Power to cooling fans 

 

New off shelf generic ignition switch

1 wire from batt to switch, 1 wire from switch to dis, 1 wire from switch to starter solenoid

 

custom trans mount

custom motor mounts, lower for hood clearance. 

custom length drive shafts

Transmission adapter, if needed

 

 

 

Cooling will be a significant factor, might have to cut hood vents. I don't think a custom rad is required, but a good quality two row all aluminum rad with two high cfm fans would be a good starting point. 

 

You will most likely need to massage the fire wall. How much? Dunno. Probably not nearly as much as would be needed to fit a 4.0 

 

also will need to cut trans tunnel to accommodate where the shifter will come through.

 

also also, which side is the t-case on. MJs use driver drop.

 

I wish you the best of luck.

If you would please consider documenting the process so the rest of us can enjoy the build.

[DirtyComanche]

1980 will be passenger drop tcase.  But they're normally clocked down so extreme that you probably won't have to cut the floor.

 

Honestly it shouldn't need firewall work, but what do I know, I never did it.  A SBC with a short water pump is considerably shorter than a 4.0L though.

[Jeep Driver]

1 hour ago, DirtyComanche said:

1980 will be passenger drop tcase.  But they're normally clocked down so extreme that you probably won't have to cut the floor.

 

Honestly it shouldn't need firewall work, but what do I know, I never did it.  A SBC with a short water pump is considerably shorter than a 4.0L though.

Mid 90s IIRC has the 700r4 with a driver's drop. 

That's the trans he'd want anyway. 

He'll have to figure this out on his own, if he's serious about it. 

 

FREE gets extremely expensive, that's another lesson he'll have to learn. :)

[zomeizter]

OP, you need welding and fabbing experience and some cash but you should be able to keep it affordable if you do your research and your own work. My 86 will get a SBC/LSx or a Mopar 5.2/5.9 depending on which NV4500/5600 tranny I find first (GM or Dodge). 

[Eagle]

It will fit -- WITHOUT CUTTING -- but it's a tight fit. Many have gone before you. The biggest problem you face is cooling. Every SBC I've seen in an XJ or MJ has had cooling issues.

[DirtyComanche]

5 hours ago, zomeizter said:

OP, you need welding and fabbing experience and some cash but you should be able to keep it affordable if you do your research and your own work. My 86 will get a SBC/LSx or a Mopar 5.2/5.9 depending on which NV4500/5600 tranny I find first (GM or Dodge). 

 

Have you seen how large a NV5600 is?   I'd never put one in a MJ.  They weigh 360lbs.  No, that's not a joke or an exaggeration.