4.0L head swap question in

[raser13]

Hey guys, I'm looking at puting a AMC 258 i6 / 4.2l out of an '83 vehicle into my '80 jeep. No biggie there. But I'm looking at possibly doing a few upgrades while I'm at it. One being a swap to a 4.0L head. There's a couple at my local bone yard to choose from. What i wa wondering is if i swap heads will i have to get different length pushrods? And ic so how would i determine what length i would need? Or is it just as simple as buying a set for the year of head i bought?

Are there any other concerns to concider? Like years to stay away from? Better years to get? Things like that. Thanks guys.

 

[raser13]

Ok. Goofy add on question I've been reading up on some of the 4.0L engine swaps and i noticed something odd about the AMC 258 i6 / 4.2l that i have. It doesn't have the standard accessories configuration for an 83 Concord, which is what i got the motor out of. But it does have what has been described as the odb2 configuration. I was wondering are there any markings on the head and motor to tell what year they are? Or if the head is off of a 4.0L? I'm just wondering if someone put a 4.0 in this concord or maybe did the head swap on it.

 

[hole]

A picture would help immensely

 

[tinman]

Yeah, need pics. When I did mine, I used a 1991-95 7120 casting head. The 1996-98 0630 casting is just about the same, but doesn't have a threaded hole for the temp sender. I'm pretty sure an easy way to check if it's a AMC 258 i6 / 4.2l block, is to see if it has a mechanical fuel pump mount. I'm not sure what some people's issue with the push rods is, I just used my old one's out of my 84 block, worked perfect. I was told by my engine shop that hydraulic lifters basically do away with issues related to length.:dunno:

Also, accessories could be different depending on if it's a California model or not.

 

[FUBAR Jeeper]

Did the Grand Cherokee use the same engine and head casting as the XJ? The boneyard here has close to a dozen Grand Cherokee from the mid to late 90's.

 

[Neuner]

Did the Grand Cherokee use the same engine and head casting as the XJ? The boneyard here has close to a dozen Grand Cherokee from the mid to late 90's.

Difference is in the PCM depending on make and year. GCs didn't come with a manual tranny which is a minor difference. Some of the later GCs have the security system integrated with the PCM but I don't think that started until '99+ but I could be wrong. If it's not disabled before being removed from the vehicle, it can lock itself up and not used again. Heard that you can get them 're-programmed' but either not easy to do, not cheap or difficult to find someone willing.

My engine, wire harness and PDC came from a '98 ZJ but the PCM is from a '98 XJ with no security and a manual Transmission .

My system is OBDII. Only difference for sensors is an added O2 sensor downstream for a non-California version. Does not have a convenient MIL light for your dash BUT has the cool Data Link for BlueTooth connection to your phone for live update of sensors, codes and information which is what I use.

These are notes from my research when I performed a swap. I have not personally verified nor do I guarantee;
- XJ and ZJ 4.0 engine blocks interchange
- 91-95 YJ and 97-99 TJ blocks will interchange in XJ/ZJ
- 00 TJ and WJ 4.0 engine blocks interchange
- 00+ XJ/ZJ blocks and '00+ TJ/WJ blocks do not interchange without significant mods
- 99-00 TJ/WJ engine blocks underwent clean sheet design changes effective in the 99 WJ and 00 TJ. These blocks are not interchangeable with XJ/ZJ engine blocks. The reason is motor mount bolt holes and belt driven accessory mounting bolt holes are in different locations or not present at all, TJ/WJ vs XJ/ZJ. May not matter for a head only swap.

- ZJ: 93-98 Gen 01
- WJ: 99-04 Gen 02
- YJ: 97-95 Gen 01
- TJ: 97-06 Gen 02

 

[73CJ]

There is a clearance recommend even though they are hydraulic. There are several different lengths and many articles on the net that can explain it way better than I. Put your old ones in, measure the gap remove and measure the push rod. Add or subtract to get the correct clearance and that's the length you need.

Sure lots have just slapped their olds ones in and it ran. Could it run better if done right? I didn't want to guess.

I got PS brackets from the junkyard Matador 70s vintage that put the PS pump high on the right side.

My CJ swims a lot and high is good.

 

[Bent]

4.0 heads use 1/2" head bolts. 1983-1985 AMC 258 i6 / 4.2l heads use 7/16 head bolts. find an older motor if you want to do a 4.0 head on a AMC 258 i6 / 4.2l .

 

[hole]

4.0 heads use 1/2" head bolts. 1983-1985 AMC 258 i6 / 4.2l heads use 7/16 head bolts. find an older motor if you want to do a 4.0 head on a AMC 258 i6 / 4.2l .

Or just use sleeves/shims

 

[Bent]

Or just use sleeves/shims

I didn't know such a product was available. Thanks

 

[CJAKE7]

There is a pile of information about the subject in this thread:

http://www.jeep-cj.com/forums/f2/258-4-0-head-swap-results-8500/

I'm thinking about doing the same thing and reading all 16 pages is a good starting point.

 

[CJim7]

I didn't know such a product was available. Thanks

Yep. Clifford and a handful of other aftermarket guys have them available. I used them when I did up my '87 AMC 258 i6 / 4.2l . They worked great.

 

[hole]

IIRC I got mine at Summit Racing

 

[tinman]

I didn't know such a product was available. Thanks

It's what I used. The machine shop that did the work on my head had them in stock.

 

[Strike]

To the OP, it would still really help to identify the engine you have for certain in order to provide accurate advice for your situation. If the engine really has OBD2 sensors it was certainly replaced in that Concord as OBD2 wasn't even a thought in 1983 and the original AMC 258 i6 / 4.2l in it wouldn't have been fuel injected.

My CJ is still in the process of my restoration but I've completed the engine work on it consisting of the 4.0 head swap and the junkyard MPI conversion as well as the installation of a mild FI-specific cam. It's all running fine so I can attest to what's involved in that.

As some have said already there is a difference in pushrod length between the two heads/engines but it is very small and some have been successful just using the original rods instead of replacing them.

www.cranecams.com/pdf-tech-tips/hydro-lift.pdf

This is a link to a guide by Crane cams (I have no affiliation) that I found in order to check for proper preload and know whether you need longer or shorter pushrods. I'm currently running the original AMC 258 i6 / 4.2l rods and it's running fine but before I complete the restoration and put it back on the road this is the guide I'll be using to verify them and will swap them out if necessary.

As for the head casting. I used the 7120 casting as some have said that it is the easiest because it still has the same coolant temp sensor tap that will allow use of the original CJ sender. Read up on the swap in the links others have provided as there are a few coolant passages that will need to be plugged in the head as they're not used on the AMC 258 i6 / 4.2l block. I was lucky as my AMC 258 i6 / 4.2l is an '86 and used the 1/2" head bolts so I did not need the shims but they are readily available from many sources if you have the smaller bolts. I also probably could have gotten away without plugging the unused passages as some have with the wider-deck blocks like mine as there's no overlap and the head gasket would have sealed it but I did it anyway for peace of mind.