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Old 06-22-2008, 04:22 PM   #1
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4.2 to a 4.0

Thinking about trying a project wondering if anyone knows the difficulty and maybe has done it? A Done 4.2 carb motor to a4.0 fuel injected on a 90 yj? Any info would be great.


Thanks

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Old 06-22-2008, 06:10 PM   #2
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pretty easy swap, i'm doint it in my 87. the motor mounts are the same, the block is almost the same, no real modification. you'll need computer, fuel pump, wiring harness, accessories off the top of my head. do you have an engine yet, i have a bare 4.0 block thats been machined .030 over i'm not using anymore

but it is much easier to get a whole assembly, i found mine with everything, wiring computer, accessories, even radiator all in one shot for cheap.

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Old 06-22-2008, 11:47 PM   #3
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Im really thinking of going that route since i found a jeep lifted with 12.5 33s and a perfect(i would eat off of) frame. Im just hitting headache after headache with my 95 that i got for $550 last summer. And by headache I mean wallet ache too. Have you heard of a 4.2 stroker with the 4.0? Ive sen some kits but not latley. Info on your install?
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Old 06-23-2008, 07:29 AM   #4
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you got a wrangler for $500???? no matter what its a deal.

i'm building the stoker you're talking about. there's some options on how to do it, but its really an easy build, basically same as rebuilding an engine. i'm putting 4.2 crank and rods in the 4.0. bored .030 over makes a 4.7 liter. you will need bigger injectors, mustang 5.0 seem to be a common choice. and the 4.2 crank needs to be cut down slightly on the nose to run 4.0 serpentine system. usually have to run premium fuel to.

i love the straight six, and this is pretty cool getting as much and sometimes more power than a 350 out of it.

here's some good ino http://www.jeep4.0performance.4mg.com/stroker.html
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Old 06-23-2008, 08:32 PM   #5
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alright so if i wanted to do this swap basically other than the motor with accessories i would need the computer? how about going from a auto trans to a man trans?
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Old 06-23-2008, 09:39 PM   #6
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from auto to manual, you'll need the slave cylinder and all, see if the swingset is already in your jeep. (the brackets for the clutch pedal) i'm not sure if they're there on jeeps or not. you need complete wiring harness to go w/ the engine and computer, did i say fuel pump already? probably got to change drive shaft also, t case splines might be different w/ 4.2 than 4.0 can't remember.

its not too bad, and you'll love the 4.0, do it.

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