options???

City
White Rock
State
NM
#1
OK all, My 82 258 with a 4.0 head and MOPAR EFI conversion is knocking, the local shop thinks its a wrist pin but regaardless I need to address the 258 portion of the engine. Seems my options are to simply buy a rebuilt 258 and swap the head and EFI and put it in. Probably easiest but not cheapest, buy a later 4.0 complete and swap it in. Maybe the cheapest but not th easiest I dont think. I have a 904/999 TF auto trans now, Id like to keep it as it has relatively few miles since it was rebuilt but if I go 4.0 it may be easier to go to an AW4 behind it, but that drives up the cost and eats up the savings from the engine. Im saying the 4.0 is cheaper because I found one semi clost for $250 with 84k miles out of a 99. I ASSUME that given my existing head EFI set up that the 4.0 would be fairly straight forward but im not sure. Fresh rebuild or relatively low miles salvage?

thoughts? what options have I missed? I am going to talk to one place about a 5.3 LS but I dont think its affordable unless I raid the IRA much more deeply than I want to.

thanks
 

John N

Addicted....Ex-SOA VP
LIFETIME
CJ-8.com Member
SOA Member
City
Rockville
State
VA
#2
Go with the complete 4.0, sell off the MOPAR EFI and head and you’ll probably break even on the whole deal. I think that I’ve read that the MOPAR EFI isn’t available any more, so it should bring a decent price.
 

jammer1

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Maple Hts.
State
Oh
#3
With the complete 4.0, it also counts if you can get the complete engine, wiring and fuel pump setup. If you don't get them, the $250. is just a drop in the bucket.
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
#4
I pulled the 258 out of my red Scrambler and swapped in a complete 4.0. I put the Mopar MPI that was on my 258 on to the 4.0. Simple, fast, easy, cheap swap. If you sell the Mopar MPI kit I will be interested in purchasing it :thumbsup:
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
#5
My 258 with Mopar MPI swap to a 4.0, add the 258 Mopar MPI.

I used all my 258 front accessories/brackets/Harmonic balancer. I changed water pumps, so look into that.

I used the 258 motor mounts/engine brackets/frame brackets. Had to use one metric bolt on driver side.

I used my stock flywheel/starter/bellhousing/etc. You should be able to bolt your flex plate up to the 4.0 crank.


Starts at post #1409:

https://www.cj-8.com/threads/anothe...trip-update-body-on-frame-again.24692/page-71

You already have all your wiring and plumbing done. Won't have to move your transmission, so no driveshaft or shifter modifications necessary.

If I was in your shoes, the 4.0 swap is the obvious choice. It will be fast, inexpensive, easy :twocents:

A 5.3/4L60E would be nice, but that will be way more expensive/involved swap :twocents:

You could probably swap in the 4.0 in 1-2 weekends :twocents:
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
#6
The only other "project" I want to add to my Red Scrambler - an inside the fuel tank pump. I am still running the Hesco external pump on my Red Scrambler. The 4.0 header runs closer to the driver side frame rail. I ran my supply/return lines down the DS when I had the 258, no problems. With the 4.0, it started the "hot fuel" crap.

I will probably leave the external fuel pump, tied into the stock gas tank sending unit, as a back up. I will then install either a Phantom 200 or Tanks Inc pump inside the tank, like I did on my green Scrambler. Internal pump for hot fuel crap, external pump as emergency back up :thumbsup:

One other potential fuel line modification - Swap in a the single line fuel rail on my red Scrambler like my green Scrambler has. This moves the pressure regulator back to near the tank, eliminates one whole fuel line, eliminates hot fuel from going back to tank :twocents:
 

Belizeit

CJ-8 Member
CJ-8.com Member
City
River Ridge
State
La
#8
I pulled the 258 out of my red Scrambler and swapped in a complete 4.0. I put the Mopar MPI that was on my 258 on to the 4.0. Simple, fast, easy, cheap swap. If you sell the Mopar MPI kit I will be interested in purchasing it :thumbsup:
If spankrjs ends up not wanting the Hesco EFI system I would like to be next in line for it. Thanks
 
City
White Rock
State
NM
#9
thanks Gents sounds like the consensus is to go with the 4.0L

I'll look at your thread Spanks Thanks, so you were able to use the mopar CPS and bracket/damper trigger on the 4.0? Interesting. I was concerned about how to trigger the thing but it may be pretty much a no brainer. why did you go with a 4.0 after already having the hybrid? Difference in drivability with the 4.0?

I have a TF 904/999 auto in mine, I assume that it will mate to the back of the 4.0 block? You mentioned you have an AX15 bellhousing on yours, because?

thanks guys, I have some reading to do and some $20s to print....
 
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HighSierra CJ

Scrambler Enthusiast
LIFETIME
CJ-8.com Member
City
Ducor
State
Ca
#10
thanks Gents sounds like the consensus is to go with the 4.0L

I'll look at your thread Spanks Thanks, so you were able to use the mopar CPS and bracket/damper trigger on the 4.0? Interesting. I was concerned about how to trigger the thing but it may be pretty much a no brainer. why did you go with a 4.0 after already having the hybrid? Difference in drivability with the 4.0?

I have a TF 904/999 auto in mine, I assume that it will mate to the back of the 4.0 block? You mentioned you have an AX15 bellhousing on yours, because?

thanks guys, I have some reading to do and some $20s to print....
I have a TF999 behind a 4.0 block. No problems.
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
#11
thanks Gents sounds like the consensus is to go with the 4.0L

I'll look at your thread Spanks Thanks, so you were able to use the mopar CPS and bracket/damper trigger on the 4.0? Interesting. I was concerned about how to trigger the thing but it may be pretty much a no brainer. why did you go with a 4.0 after already having the hybrid? Difference in drivability with the 4.0?

I have a TF 904/999 auto in mine, I assume that it will mate to the back of the 4.0 block? You mentioned you have an AX15 bellhousing on yours, because?

thanks guys, I have some reading to do and some $20s to print....
I have a stock 258 bell housing bolted to the 4.0. I have an adapter between the CJ bell housing and the AX15. I would imagine your auto will bolt up to the 4.0 block, no major problem.

The Hesco crank positioner bracket bolted right to the 4.0 oil pan. I might have had to overdrill a hole or two in the bracket, but no big deal. The balancer bolted to the 4.0 crank snout. I was worried about this, no problems so far.

I went with the 4.0 because I got it for a good price, cheaper then I could have rebuilt the 4.2.

The 4.0 revs easier, better at higher RPM's, the 258 was a bit better off idle. The 4.0 still works fine off road. I just have 33's with 4.10 gears. Perfect with the 258. If I would have known that I was getting a 4.0, probably would have went 4.56. Everything works fine how it is, but I think the 4.0 likes slightly higher revs. You also have to remember, I have been daily driving either a TJ or LJ Rubicon since 2005, both stock tires and gears. So, I am a bit biased toward over gearing now LOL.
 

CJ7Pilot

18436572
LIFETIME
CJ-8.com Member
City
Yuba City
State
CA
#12
I've showed up late to this party... but I really have to vote for rebuilding the 258 block!

I've had a stock 258/5-speed (first a T5, then an AX15) in a CJ7, then the same 258 with MOPAR MPI, then rebuilt, then with a 4.0HO head.

I've also had a 4.0 HO/automatic in a Cherokee.

Now I have a 350SBC/4-speed in my Scrambler.

My favorite combination is the 258/MPI/HO head/AX15... loads of low rpm torque, and smooth running all around.

My next favorite is the 4.0HO/AW4 that was in my Cherokee. I'd imagine your TF999 would work out pretty well with a 4.0HO, as well.

My current 350/SM465 is tough as nails... but frankly, is not very exciting (and doesn't really belong in this conversation). I've put a lot of effort in to it though, so I'll be running it for a while.

Good luck! :cheers:
 

Belizeit

CJ-8 Member
CJ-8.com Member
City
River Ridge
State
La
#13
Interesting. Several combos to think about. I'm going with 258 / Sniper / T176. I waited to long to look for a MPI Hesco, but the wife's Cherokee with 4.0 HO is being driven and is still in the bullpen if needed. :)
 
City
White Rock
State
NM
#14
thanks again all, I have sort of come to the conclusion that I cant really go wrong, just different solutions. I THINK that Im going with a reman 4.0l the used one for 250 turns out to have been dropped and has holes in teh oil pan and distributor cap plus it looks a bit weathered with duct tape shards over the throttle body so Im going to shy away from it unless the core charge on the new 4.0 is great than the 250 ish hes asking (it was 220 today).

still need to run premium with the 4.0? I didnt with my 4.0 MJ but it was an 89 with the renix system. did it matter what year 4.0 model you got? I assume I'll have to order for a particular year XJ or YJ or whatever

If I get another offer to buy the darn thing before next week I may take less cash and run away, Ive had 2 offers in the past two weeks before I decided the knock was terminal but no follow through on their parts at the amount I told them I wanted for it.
 
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