XJ Head Swap need help!

[BurgleXJ]

Okay. So. Fml. I bought a straight clean lifted 93 Cherokee for $600 it was a smokin deal it ran and drove well just a tranny pan gasket... Yeah right. Long story short the dude didn't tell me it had a blown head gasket. We rip the head off and noticed it's cracked through the 3rd cyl so we go to buy a new head for the 93 Cherokee we wanted a Power Torque 2A30. It doesn't match. I find i have a 5010341 block with a beautiful crack in my 0630 head. Can someone help me figure why these numbers don't match the year? The parts guy says i cant order the 93 head because it doesnt match the numbers of the 97 head. Which also meant he wouldnt accept my core. He then said they wont take the core anyways because the head is cracked unrepairable. I understand how numbers work obviously but wtf why else do you buy a new head. I say bs. I call my mechanic who has worked on a ton of xjs. He said there's no way someone put a 97 engine in my 93 xj. He said the intake manifold would be different and it wouldn't work. He said the parts guy is full of it and they should take the core. Basically i want to know what I'm dealing with. What's the likelihood someone swapped engines from a 97 into this 93 or is it a body fake? Also clearly my block number is 5010341 and my current cracked head is 0630 what head should i order for best performance and no mods. I do however have a 90 xj fully intact if i can Frankenstein something. I need to know my options to get a head on this beast. Please help.

 

[8Mud]

I don't know the specifics of your situation. But in similar situations I bought (borrowed an returned ) likely gasket sets. If the gaskets match you are good to go, other than sensor differences. A cheepo gasket set will work just fine for this.

 

[Hypoid]

C-O-R-E is an acronym. The last two letters stand for "Rebuildable Exchange." A cracked head casting does not meet standard criteria for rebuild/refurbish. If your mechanic claims to repair cracked castings, I'd like to see pictures of the process.

 

[Jeep Driver]

Be it a '93 or a '97 block, they are identical.

Take the head off your '90 and have it rebuilt. The '90 and '93 heads are identical.

Or, buy a new head for a '93, eat the core charge.


This is not rocket surgery.

 

[Tim_MN]

Any XJ 4.0L block and any 0630 or 7120 head will interchange. Previous owners may have swapped some stuff.

Find a good used 0630 or 7120 head at the junkyard, have it inspected, consider having it rebuilt, and bolt it on.

 

[BurgleXJ]

Thanks guys. The head gasket check is a good idea. I found another head at another store that is a 0630 replacement. What differences if any is a 97 intake and exhaust compared to a renix? Also yeah sucks about the core may try and hide the crack to save 100 hopefully parts guy is dumb lol. Any advantage to buying a 7120? If I'm researching correct the 7120 doesn't have the block pin holes like the 0630? Does a renix?

 

[Ecomike]

The '90 and '93 heads are identical.

I am pretty sure the 90 and 93 are different. The 90 is the last year for the Renix engine and head, 91-96 is the same head I think, HO.

But the main difference between 90 and 91 is the intake-exhaust manifolds. I believe some people here have used the 87-90 and 91-96 heads interchangeably, but there is some kind of issue on the manifolds and their gaskets (not the head gasket) issues to deal with when you do that. I have done one, but there are threads here covering it already.
I would go to a machine shop, have them buy a Junk Yard core, service it and pay the machine shop for the ready to use, used head (with warranty). I have done that before with good results.

 

[Ecomike]

Any XJ 4.0L block and any 0630 or 7120 head will interchange. Previous owners may have swapped some stuff.

Find a good used 0630 or 7120 head at the junkyard, have it inspected, consider having it rebuilt, and bolt it on.

X2!!!!

 

[90xj06]

The 91-96 head the intake ports are smaller and higher. You would use the 87-90 intake gasket if it was going into a renix.

 

[BurgleXJ]

What's the price difference in junk and service vs parts store reman? I'm ready to order one tomorrow for 450 out the door. I'm not opposed to junkin but got a baby coming in 2 months and i live in a rural area what's a highball for junk price then reservice?

 

[Ecomike]

My local machine shop wanted $200 for a good Renix 87-90 4.0 core, and up to $250 for complete servicing. I found a head for $25, but taking about 12 weeks to get it Naxja-pony expressed to me across state.

Does the remain include the rockers, the pivots, bolts and rods? If yes, it sounds like a good deal.

But I have bought entire used running 4.0 engines for $150, and entire Jeeps for $450.

 

[BurgleXJ]

Got the new head ordered it only comes with valves springs and seals but everything else i still have is in great condition so I'll be using the old rockers and rods. My next question is what is the "breaking in" process with a new head and gasket? When do i torque again?

 

[md21722]

There is no break in. You should change the coolant and oil a few times after the work is done. Otherwise just drive it. Some folks change the oil as soon as it comes up to operating temperature. You will always get grit in the oil & coolant from doing this work. Be aware there is a multi-stage torque process and the front drivers side bolt takes a lower torque & some thread sealant because it goes right through a coolant passage.

 

[BurgleXJ]

Thank you. I'll have to google the fsm specs for torque pattern and lbs. What would y'all recommend for the front bolt? Thread locker or a gasket type?

 

[Ecomike]

Copper silicone sealant, nothing else for the thread sealant.

 

[BurgleXJ]

Thank you definitely a will do.

 

[md21722]

Thank you. I'll have to google the fsm specs for torque pattern and lbs. What would y'all recommend for the front bolt? Thread locker or a gasket type?

Loctite 592 is factory. It's thread sealant. Not thread locker or gasket type.