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Discussion Starter · #1 ·
I was wondering what the wiser choice would be.. springing the $$ to fuel inject my 258(great condition) or find myself a 4.0 liter in good shape? I will be moving to CO from FL in a little while and the dang carb doesnt run good here..i dont even want to dream of it working at altitude or cold. Those fuel injection kits are pricey, but the 258 is great(other than the carb). On the other hand, a 4.0 can easily be found down here as left overs from a rear end wreak...

 
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Discussion Starter · #2 ·
What about finding a late model 4.0 and take the head and fuel injection. You will get a nice HP incress with the 4.0 head, and better drivablity with the fuel injection. Plus you will keep the lower bottom end with the 258. If you do the 4.0 head you will need the exhaust manifold for the 4.0 as well.

'95 Cherokee; '86 CJ-7, HEI upgrade
'84 CJ-10a, running stock; '84 CJ-10a, running stock; '84 CJ-10a, running stock; '85 CJ-10a, needs alt & vacuum pump.
 

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Will you need to replace harmonic balancer if you put a 4.0 head and F.I. on the 4.2? I have an opportunity to strip a wrecked '92 4.0, and would like to know what additional parts I need to purchase.

'84 CJ-7, 4.2, 3.5" Lift, 31's, YJ tub, TR upgrade, Moser 1 piece, LED's.
 

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I dont' think in this case there is a blanket 'one is better' solution. It really depends on what you are looking for.

If you are building it primarily for rock crawling, I would go MPI and 4.0 head on your 258 block. That combo has much more down low torque due to the longer stroke, but you still get most of the benefits of having the better breathing 4.0 head and the reliability of brand new mpi parts.

If you are really looking for a great all around motor for a Jeep, you can't go wrong with the 4.0 swap. It will almost always be a little cheaper, but that doesn't always mean it will meet your needs the best. I think it really depends on what you want out of it.

I have gone even further by having a stroker 4.0 short block built and I have to say it really is impressive, not necessarily the cheapest solution however.

Do some reading. There is no right answer, but the more you understand going into it, the better fit you will most likely find. There has been a ton already covered on this topic in the last year.





-raymo
4.6 Stroker Scrambler
 
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Discussion Starter · #6 ·
Thanks for the help. I am now seriously consiering the 4.0 head and injection swap. I guess i will have to play this one by ear and see what falls into my hands.


 

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How much do you want to spend? I can probably make something fall into your hands cheap if you are moving to Colorado. I come across this stuff all the time. I know that this isn't the for sale board, but I need to clean out my garage and come up with some extra money for the down on our new property.

 
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