4.0 Head/MPI swap to 258

I’m planning on swapping a 4.0 head onto my 79 258 and I found a running XJ for less then I could buy just the 4.0 head at a bone yard. I will be picking this up tomorrow and would appreciate some info on what needs to be pulled.

Besides: 4.0 Head, valve cover, exhaust manifold, O2 sensor…..

The 4.0 Head seems like a straight forward swap but this 93 XJ has a MPI and if it’s not too difficult I would like to swap this over as well. I haven’t seen any write-ups concerning the swap but do know I need the ECU, wiring harness, injection, fuel rail, intake and sensors. Anything else?

Machine the bellhousing or buy the harmonic balancer kit?
Use the XJ MPI or Mopar kit?

Your thoughts.....

 

Do a Google search for 4.0L Swap, you are doing about the same thing. Also CJoffroad.com has a whole Fourm dedicated to the subject. Good luck

 

Did the goggle search for the 4.0 swap that’s clear cut what isn’t is the MPI swap. I was hopping someone here would have some experience with this rather then going over to CJoffroad.com, not that there is anything wrong with that particular site.

 

Not too much info for ya as I just swapped the whole 4.0 in. However you'll need a fuel pump. I used a ford pump off a truck, autozone po#e2000. You will need to figure out fuel lines, espicialy the return line setup.

As for the head, aren't there some differences in head bolt diameter? I thought the later 4.0 heads had to be sleeved in order to work with the 258 blocks.

I wound up sending the bellhousing to Novak to have it modified for the cps as I wanted something that looked stock. However I'm not sure they got it close enough to the flywheel as I've had some cps issues. If I was to do it over I'd probably go with the harmonic balancer kit as its easier to set,fix, and replace.

Hope that helps.
Kevo

 

Yes, but I’m ok with a 79 258, 71-80 and 88-90 use ½ bolts. The 81 -87 use 7/16 so you would need to tap the block or Clifford sells a kit with spacers to center the 7/16 bolts in a ½ holes.

Thanks for the tip on the Ford pump part # and the recommendation on the harmonic balancer, very helpful.

 

You are going to need a lot of the wiring harness from the 4.0 Be careful and dont cut wires while you are removing it from the donor. While it is pretty much a mechanical bolt in. The electronics are not.

 

I'm just happy it's the OBD1 and not 2, I plan to label all wires. Thanks for the tip.

I have read where someone had cut it down to 5 wires.

 

the Mopar kit seems to have some technical problems
a couple folks I know have had pinging and oil consumption problems
I have seen 2 rigs that installed the Howell TBI on 258s
they are happy with them
I think that is what I would do if I had the 258 or the need, go with the Howell TBI kit
sorry, doesn't help with your original question

 

Thanks for the heads up on the Mopar kit Jim good to know.

Anyways, the 93 XJ deal is off. Yesterday, we made the deal and agreed on a price I then told her I would call before picking it up today. When I called today she told me someone else had bought it yesterday for more money. I feel I’m a good judge of people and usually find out quickly what their made of. When I got off the phone with this woman yesterday I turned to my wife and told her I felt she wouldn’t keep her word and I was right so, no big loss.

The lesson on the 4.0 head/MPI swap was well worth it.

 

I purchased the Mopar Kit from Hesco. I installed it on my 1987 Wrangler and it works great! If you are doing this and the head conversion you shouldnt have any problems with ping.

I would highly recommend it.