4.0 Head, MPFI, and Serpentine on my 82 258

[ThisGuyUKnow]

The other week I picked up a 4.0 head in the junkyard and took it to the machinist to get magnafluxed and cut at three angles. Im an idiot and I overlooked the bolts under the wire cover and i broke an exhaust stud off trying to pry the head off before I realized i needed to unbolt more studs.

Pulling the head was easy as I found a 1995 Cherokee(XJ) that had been pretty much picked clean and was just a long block in an empty engine compartment.

I was going to stick with the Carter BBD but I couldn't get the thing to run before so I am just going to inject the Engine while I am at it. I am hoping to get a quiter, smoother idle, hopfully somewhere around 18 MPGs, easy cold starts, better throttle response, and longer life out of my AMC 258 i6 / 4.2l by the end of this.

Luckily I have already installed an Ax15 so I can avoid the cost of a CPS relocator. I am stealing the CPS off the nv3550 that is slotted to go behind my waggy 360 because the one that came with my ax15 was broken and the wag won't need it. It took me about an hour to remove all the accessories and get to the point where all i have to do is remove the old head bolts to lift the head off. I intent to just leave the intake on pull it whole as nothing will be retained with the new head and injection.

I ended up with 3 MPFI intakes. Two where a crime of opportunity as someone had already pulled them so I threw em in the wheel barrel, These are both 95 intakes. Then I grabbed an intake from a 00 but I dropped it and broke one of the tabs for the Power steering pump off which sucks because that intak is supposed to be the bees knees.

Hopefully I can find someone who can weld aluminum Monday and fix that tab because supposedly a 91-95 4.0 HO head/00+intake is the way to go according to the things i have read online. If not I will just slap one of the other intakes on and be done with it.

The head ran me 250 bucks and I have to pick it up Monday. I pulled the trigger on a wiring harness from a 94 automatic xj for 200 on jeepforum and then the next day found two 94 manual xj's with perfect wiring harness at a small pick-n-pull that I could have probably gotten for a 1/4 of the price. I am going to go tomorrow and pull the serp set up off one of those trucks and maybe while I am there I will get the wiring harness and use the auto one as the spare. So far I am about 500 into this if you consider the cost the pick n pull charged me for the intakes and the valve cover etc. etc. and I am figuring on about 2-300 more for the serp, manual harness, and Misc fuel delivery stuff i need.

Results of my junkyard visit

head ready to Unbolt

I pulled off

 

[ThisGuyUKnow]

 

[ThisGuyUKnow]

I took the head all the way off today and picked up the reconditioned 4.0 head today.

I was dissappointed because the cylinders look great and when I pulled the head off it was at top dead center exactly like I set this, but I was informed by a jeep buddy that this is not indicitive of rainbows and sunshine and there still could be timing chain and cylinder wear.

It is said that some 258s do not require you to weld the water jackets and some do. I think this may be dependant on what head bolts you have. I think I will have over hang and need the welded jackets because I have 7/16 head bolts instead of 1/2. Either way I think it would behoov you to use jb weld or some high heat epoxy and just seal it up...Better safe than sorry.

Unfortunately I cannot continue further on this swap Untill I get my clifford performance head bolt spacers. These will center my 7/16 bolts in the 1/2 openings on the 4.0 head. I have read that you are not supposed to reuse head bolts as they are bad joojoomagumbo but I have as of yet not been able to find any place that sells new 7/16 head bolts for a AMC 258 i6 / 4.2l and will risk reusing my originals over have the blocks drilled and tapped. So if someone has a new set or knows where to get one please PM me.

I also need to find an exhaust manifold so if anyone has one from a 4.0 layin around PM me as well and I will try to buy it from you.

Reconditioned head

Casting number and date stamp

see ya later AMC 258 i6 / 4.2l head

shot of the cylinder wall at 95k

 

[dalefan88]

ill be watching this one. i have heard alot of people having troubles with this swap but i always wanted to do it to our jeep when i had the money for it.

 

[Petescj]

You and me both. This should be a very informative thread. Thanks for sharing it.

ill be watching this one. i have heard alot of people having troubles with this swap but i always wanted to do it to our jeep when i had the money for it.

 

[ThisGuyUKnow]

ill be watching this one. i have heard alot of people having troubles with this swap but i always wanted to do it to our jeep when i had the money for it.

What problems have they reported exactly I have hears nothing but positive feed back..... Now you got me second guessing myself

 

[Petescj]

Too late now.

What problems have they reported exactly I have hears nothing but positive feed back..... Now you got me second guessing myself

 

[ThisGuyUKnow]

My greatest concern is I can not find new 7/16 head bolts anywhere. The only ones I can find is 1/2 and I am worries the used 7/16 from my block will snap when I torque them in place

 

[dalefan88]

What problems have they reported exactly I have hears nothing but positive feed back..... Now you got me second guessing myself

mostly the head bolts. as in getting the right ones. dont second guess yourself. keep at it and we will be watching i want to know how it turns out to show the wife.

 

[Sasquach]

Hesco Inc. - High Performance Engine Service

 

[ThisGuyUKnow]

129 dollars!!!!!! Oh my!!!

 

[IOPort51]

Your cylinders look good from here. the #1 is the most prone to wear because of it's proximity to the water pump. The AMC 258 i6 / 4.2l gasket will cover the extra holes in the 4.0 head. I have a welded head so I can't speak of the JB Weld option but I say go for it.
This will sound obvious but, don't over tighten the head bolts. Use the torque rating for the 7/16 bolts not the 1/2 inch you don't have.

 

[ThisGuyUKnow]

so can I reuse my 7/16 head bolts IO? SO use a stock AMC 258 i6 / 4.2l 7/16 head bolts and then torque to what the shop manual says to do for a stock 82 CJ7

 

[ThisGuyUKnow]

Today I finished up my brake booster stuff as I am still waiting on the Clifford head bolt spacers and my new exhaust manifold.

I did take the time to get packing peanuts (you are going to have to buy this I went to two parcel stores and all they had were the non eco friendly ones) and some epoxy and seal up the coolant passages.

Ok so tangent here, every 4.0 head on AMC 258 i6 / 4.2l shortblock write up has different things to say. Some say I wish I hadn't epoxied/welded the passages because I didn't need to there was no over hang. Some say there was overhang and they had to. Here is the best way to look at it. If you use JB weld,that stuff is supposed to work up to 800 deg fehrenheit. You will never ever have your engine this hot unless you are offroading on Mercury. If you are crafty you could probably get 1 thing of JB weld to do all the jackets and then your only out at most 12 bucks. I did some measuring by sketching the bottom of the head and putting that on the block and it looked like it was overlaping by a pig's butt hair. So I may have been able to get away without welding the passages;however, why risk it? these passages are blocked off by the 4.0 head gasket anyhow so are unimportant either way so why not just play it safe and seal them up then you dont ever have to find out if you were the special case that didn't need to do it....

Anyway the jb weld went on well and was easier to use than that stuff that comes in a syringe and it took me one set of jb weld tubes to do all of the jackets.




I have decided that I am just going to inspect my old head bolts for warping or thread wear and if they look good I am going to use antiseze compound on them and then split the difference between the torque specs for the AMC 258 i6 / 4.2l and 4.0 and pray they dont snap.

 

[IOPort51]

first thing, head bolts go in clean and dry no anti seize, no oil , no nothing . that is the standard. one of them gets some pipe sealer but I can't remember which one. A good thing is to run a tap down the hole to make sure they are clean. The tap should take very little effort.
I used the old bolts and the Clifford bolt spacers to center the head , is it the best thing to do? don't know but I did it and would more than likely do it again. If your engine comes un put together, it was a foolish thing for you to do.
Torque the bolts to the rating on the bolt not the head, If you tighten to the AMC 258 i6 / 4.2l spec and pull everything down even you will be just fine, this increases the air flow not the compression to any real amount. Relax, pay attention to detail and everything will be fine.
This is my .02.

Today I finished up my brake booster stuff as I am still waiting on the Clifford head bolt spacers and my new exhaust manifold.

I did take the time to get packing peanuts (you are going to have to buy this I went to two parcel stores and all they had were the non eco friendly ones) and some epoxy and seal up the coolant passages.

Ok so tangent here, every 4.0 head on 258 shortblock write up has different things to say. Some say I wish I hadn't epoxied/welded the passages because I didn't need to there was no over hang. Some say there was overhang and they had to. Here is the best way to look at it. If you use JB weld,that stuff is supposed to work up to 800 deg fehrenheit. You will never ever have your engine this hot unless you are offroading on Mercury. If you are crafty you could probably get 1 thing of JB weld to do all the jackets and then your only out at most 12 bucks. I did some measuring by sketching the bottom of the head and putting that on the block and it looked like it was overlaping by a pig's butt hair. So I may have been able to get away without welding the passages;however, why risk it? these passages are blocked off by the 4.0 head gasket anyhow so are unimportant either way so why not just play it safe and seal them up then you dont ever have to find out if you were the special case that didn't need to do it....

Anyway the jb weld went on well and was easier to use than that stuff that comes in a syringe and it took me one set of jb weld tubes to do all of the jackets.




I have decided that I am just going to inspect my old head bolts for warping or thread wear and if they look good I am going to use antiseze compound on them and then split the difference between the torque specs for the 258 and 4.0 and pray they dont snap.

 

[ThisGuyUKnow]

I was looking at the bottom surface of the head and there seems to be some residue from the jb weld that had to be wiped off... SHould I take it to the machinist and have them resurface the head to rub some of this off or should it still be able to make a good seal?

 

[IOPort51]

use the flat of a file to take it level, see draw file.

I was looking at the bottom surface of the head and there seems to be some residue from the jb weld that had to be wiped off... SHould I take it to the machinist and have them resurface the head to rub some of this off or should it still be able to make a good seal?

 

[ThisGuyUKnow]

Well I am gettin anxious. The Clifford spacers are not going to be delivered
till tues because of memorial day. I think tomorrow I will bolt together my intake components so everythingbwilm be on it ready to wire up. Tuesday I amfoing to go pull that manual xj wiring haress and maybe the serp setup as well.

I am going to do like io says with the head bolts and make sure the bolts/bolt holes are clean an reuse the bolts usin the AMC 258 i6 / 4.2l torqe specs.

Hopefully my new exhaust manifold will get here ties as well so I can take IO's advice and install the exhaust andintake manifolds before dropping on the heads.

 

[Trapshooter]

Good luck with your mod. For a guy who doesn't know much about A/C you sure seems to know about everything else!!

Keep up the good work.........Trap

 

[ThisGuyUKnow]

Yea I am still confused about the ac. I also am not sure how I am goin to make the fuel delivery work either. Most other things here I got a decent grasp on.