4.0 head for 4.2 engine anyone? - JeepForum.com
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post #1 of 5 Old 12-15-2001, 05:29 PM Thread Starter
jerk with a jeep
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4.0 head for 4.2 engine anyone?

Has anyone installed a 4.0 head on a 4.2?
I wan't to a local dealership "I was there to pick up a part for my YJ" and I asked the guy behind the parts counter if a 4.0 head would fit a 4.2 block. He said no. Today I found information on off road .com that expliains
the process. Is there anyone here that has done this conversion? I think I am going to do it. What do you guys think? There is one thing that concerned me, and that is using high temp epoxy to plug some of the water passages, is there any reason why this would be a problem?

1989 YJ 33's and 4" lift 2"BL 4.2

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post #2 of 5 Old 12-15-2001, 06:07 PM
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i was planning on doing that same conversion.
If I would do it, I would do something else about the water jackets, I dont like the idea of the epoxy either. If you buy a 4.0L cylinder head, make sure you get one newer than 91, and try to grab all the fuel injection stuff to go with it.

Found a 85 CJ7 tub in good shape with
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post #3 of 5 Old 12-15-2001, 07:50 PM Thread Starter
jerk with a jeep
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If you get started before me let me know how it goes. I was thinking about going with a Holly four barrel and Clifford research intake and headers.I've used thier stuff before on sixes and had really good luck with it. From your message you feel EFI would be the way to go. When I do it I most likely do it in stages, head first and then carb or EFI.

1989 YJ 4" lift & 2"BL 33" swampers
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post #4 of 5 Old 12-16-2001, 12:25 AM
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Check out http://monsterslayer.com/jeep/40Head/40Head.htm for info on converting your 4.2 to 4.0 head.

"If It Aint Broke, Fix It Till It Is!!!!!"
05 TJ Rubicon, 4.0L, 6 Speed.
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post #5 of 5 Old 12-19-2001, 06:32 PM Thread Starter
jerk with a jeep
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Still contemplating installing a 4.0 head and would like to hear from anyone that has done
this conversion. I would like to know if it will be durable. Has any one had any problems with this conversion, and how has your jeep worked since the conversion? Please let me know.
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