4.0 transplant

Call me crazy but I was offered a deal on a 95 Grand cherokee with 4.0 245000 miles. Ok, i have a 90 XJ ( not my beater XJ ) with 4.0 100000 miles. I know the fuel injection is different but is the block and head the same? Can i just swap everything over? Meaning take everything off the 95 block+head and puttin it on the 90 block+head. I know the old fords with the 300s could be done, but not sure with the 4.0
Thanks for any input

Yes, but it may be worth it to "freshen" the head on the 95 and swap it over along with the newer intake/throttle body. That way you get the HO head too.

Yep, you should be able to just swap everything over. You will also need the throttle cable and TV cable from the donor vehicle. You will use all your sensors on the 90. The TPS will have to be adapted to work with the HO Throttle body. You can either buy an adapter, or adapt it yourself. Id just buy the adapter.
Blocks are very similar but not the same (i think they were not as strong as the RENIX era aka your 90) Everything from the head up is different. Thats ok though cause the RENIX head sucks, and the HO head is great (casting 7120). They block and head will bolt together however, they are not different in that since, just different in function.

Thanks guys for your come backs.

I don't understand which way your are swapping. The 95 has more miles than the 90, so I assume you are going to sacrifice the XJ for the ZJ? If it is the other way, have the head work done on the 95 and use it on the 90 head.

If you use the intake and exhaust manifolds with the head, you will be ok. The alignment is different between the 90 head head and the 91(HO) and up manifolds but some have made them work.
There are article about how to adapt the newer TB to the RENIX environment. Do a search.

I don't remember when they moved the MAP sensor from the firewall to the TB. That would be another item to check.

The 88-90 blocks had a higher nickel content which made them ware longer.

#1

yellowta said:

Yes, but it may be worth it to "freshen" the head on the 95 and swap it over along with the newer intake/throttle body. That way you get the HO head too.

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Rework the head off the 95 to make everything go back together better?

Muad'Dib said:

Yep, you should be able to just swap everything over. You will also need the throttle cable and TV cable from the donor vehicle. You will use all your sensors on the 90. The TPS will have to be adapted to work with the HO Throttle body. You can either buy an adapter, or adapt it yourself. Id just buy the adapter.
Blocks are very similar but not the same (i think they were not as strong as the RENIX era aka your 90) Everything from the head up is different. Thats ok though cause the RENIX head sucks, and the HO head is great (casting 7120). They block and head will bolt together however, they are not different in that since, just different in function.

Click to expand...

You sayin to keep as much of the 90 together would be easier? Would i have to swap wiring harnesses?

sjx40250 said:

I don't understand which way your are swapping. The 95 has more miles than the 90, so I assume you are going to sacrifice the XJ for the ZJ? If it is the other way, have the head work done on the 95 and use it on the 90 head.

If you use the intake and exhaust manifolds with the head, you will be ok. The alignment is different between the 90 head head and the 91(HO) and up manifolds but some have made them work.
There are article about how to adapt the newer TB to the RENIX environment. Do a search.

I don't remember when they moved the MAP sensor from the firewall to the TB. That would be another item to check.

The 88-90 blocks had a higher nickel content which made them ware longer.

Click to expand...

I wheel a 88 XJ and have had a 90 XJ just siting around for parts. Like i said im getin a deal on the ZJ. The ZJ runs good, I was just thinkin about the future and if this 90 4.0 would save the day if something bad happened.
I will do a search.

J-Man said:

You sayin to keep as much of the 90 together would be easier? Would i have to swap wiring harnesses?

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My understanding was that your putting the engine from the 95 into the 90.

You dont need to swap harness or anything, just the complete engine with throttle cable, TV cable and adapt the TPS. Thats just about it.

Muad'Dib said:

My understanding was that your putting the engine from the 95 into the 90.

You dont need to swap harness or anything, just the complete engine with throttle cable, TV cable and adapt the TPS. Thats just about it.

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ahhh I see said the blind man. So just unplug everything and leave the intake and exhaust on the 90 motor? Switch over the AC and alternator and rig the 90 throttle cable into the ZJ ? Also adapt the TPS.

J-Man said:

ahhh I see said the blind man. So just unplug everything and leave the intake and exhaust on the 90 motor? Switch over the AC and alternator and rig the 90 throttle cable into the ZJ ? Also adapt the TPS.

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Your confusing me now. My understanding was all you wanted to do was swap the motor from the 95 into the 90.

J-Man said:

Call me crazy but I was offered a deal on a 95 Grand cherokee with 4.0 245000 miles.

Ok, i have a 90 XJ ( not my beater XJ ) with 4.0 100000 miles. I know the fuel injection is different but is the block and head the same? Can i just swap everything over? Meaning take everything off the 95 block+head and puttin it on the 90 block+head. I know the old fords with the 300s could be done, but not sure with the 4.0

Thanks for any input

Click to expand...

If you are JUST swapping the the motor from the 95 into the 90, then what i said applies. If your trying to flip flop them for whatever reason then there is alot more involved.

I see, the 90 is a parts jeep(no title) 95 is in great shape but alot of miles. Sorry for the confusion

J-Man said:

I see, the 90 is a parts jeep(no title) 95 is in great shape but alot of miles. Sorry for the confusion

Click to expand...

So since you dont have a title in the 90 your using it for parts? The 95 is the one you actually care about driving?
If so...
The only really usable engine part for you is the block. If i were keeping the 95 running and using the 90 for parts, i would use the block and start building a stroker.

You know some would say 245000 isnt anything for a 4.0. Are you having some running problems? Low compression? If your actually having a problem and want to do this on the cheap, then steal the complete block from the 90 and bolt it up into the 95. The top end will stay the same. So you dont have to worry about adapting sensors etc. This however is a more involved process since you need to pull the engine on both vehicles. Like i said before if it were me i would build a stroker. If you still want to do this and do it not so cheap, then i would rebuild the 90 block (new rings bearings etc), and also take the head from the 95 into the machince shop and get it check out. New valve springs stuff like that. It should still all stay fairly inexpensive. (less then 500 bucks i would think). Then assemble and be done with it for many many more miles to come.
Either way you go its going to be alot of work, and both jeeps will be down for at least a couple weekends. (if you just swapped blocks)

Thanks for the help, I do appreciate it.