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post #1 of (permalink) Old 12-21-2001, 03:03 PM Thread Starter
 
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Need engine building info & advice-4.2L

I think I am going to attempt to pull and rebuild my engine. I don't know much about building engines and am looking for advice. for example, what cam and type/brands pistons? I had to do head work 2 years ago and replaced all valves at that time, is it worth it to have it ported and polished? Should I use a stroker kit? What is a stroker kit? Funds won't allow injection at this time, but I hate to put the BBD back on. Weber or Motorcraft?
My CJ is strictly a rockcrawler, so I don't think I need high horsepower; thus the decision to stick with the 4.2L. Future plans include the mopar MPFI kit, hopefully next year. I'm hoping to get this done for around twelve hundred; that's parts and machine work, I will do the pulling, disassembly and reassembly.

Any and all input welcome,

Max

82 CJ, some stuff stock, some stuff not
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post #2 of (permalink) Old 12-21-2001, 03:20 PM
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Re: Need engine building info & advice-4.2L

When we did mine exactly a year ago I bought a complete rebuild kit from NAPA. It ran about $475, all the parts, pistons, rings, bearings, gaskets, etc. were top of the line. I highly recommend the kits. You can go to http://www.napaonline.com to get the info. I have a Weber, but from what I understand the Motorcraft is good, just not the top end HP gain you get with the Weber. YOu should easily be able to do this for a grand, including buying yourself an aluminum valve cover while you're at it.

Brad
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post #3 of (permalink) Old 12-21-2001, 05:43 PM
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Re: Need engine building info & advice-4.2L

4.0 h.o top end with a short duration (about 260)
torque cam.

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empty the magazine.
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post #4 of (permalink) Old 12-21-2001, 06:03 PM Thread Starter
 
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Re: Need engine building info & advice-4.2L

A kit sounds like a good way to go to me. Did that include the camshaft? I checked out the link, but they didn't return any info on a master kit; probably have to go to a store. I don't really want to change heads; I just sunk some money into the head 2 years ago; plus the more I save on the engine work means more for other accessories. Would like some headers and another red top under the hood. How does that fresh 258 run, Brad? RPM wise, what is she comfortable at on the highway and what is the top end?

Max

82 CJ, some stuff stock, some stuff not
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post #5 of (permalink) Old 12-21-2001, 06:27 PM
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Re: Need engine building info & advice-4.2L

I agree with sickdog about the 4.0 head. Polishing and porting will help the power out some. Summit racing carries good cams. not sure of the web address though.
Tim

post #6 of (permalink) Old 12-21-2001, 06:48 PM
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Re: Need engine building info & advice-4.2L

It came with a stock cam, which was just fine with me. Runs strong, pulls as many rpms as I want it to. Make sure you get the chromoly rings, and make sure the machine shop you take it to knows the proper crosshatch to put on the cylinders to get the rings to seat. There have been many people complaining about not getting the rings to seat properly, mine seated immediately. The only problem I have had is the cold idle problem I posted about the other day, but it has no effect on the way the engine runs, and it doesn't have anything to do with the rebuild, its either carb or ignition, not sure which yet. If you go with the 4.0 head you have to go FI, then you just start spending money. We did my motor, bought the best of everything including an aluminum valve cover, and with machining it wasn't over a grand. And yes, I had to go to my local NAPA store, they put the kit together from parts at the warehouse, they aren't prepackaged.

Brad
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post #7 of (permalink) Old 12-21-2001, 08:19 PM
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Re: Need engine building info & advice-4.2L

I just finished a rebuild on my 4.2 this summer. I had the machine shop order quality parts they cost me about 500 and the machining cost me about another 500. I would definitely go with 4.0 head before any other engine mods. Besides for MPI, what else will give you 40hp!? Not headers. If you want a cheap carb until you get MPI you may try to Rochester I've been very happy with mine, it costs less than half as much as a Weber and you will get much better performance than with any carter.

When in doubt, whip it out.
post #8 of (permalink) Old 12-22-2001, 05:01 PM
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Re: Need engine building info & advice-4.2L

competition cams has the best torque and off road range cams.
and a set of standard rings are fine. i don't believe there IS a such thing as chromemoly. it's one or the other.

when in doubt.........
empty the magazine.
post #9 of (permalink) Old 12-22-2001, 05:11 PM
 
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Re: Need engine building info & advice-4.2L

Call around to the junk yards a look for a whole new 4.0, they arn't that hard to put into cj's and will have more power than your 258 and then when you get more cash you can put your 258 crank and special pistions in and make it a 4.5L stoker.

BarrelRoll

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post #10 of (permalink) Old 12-22-2001, 06:20 PM
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Re: Need engine building info & advice-4.2L

A 4.0 is not as good a crawling motor as a 258, take a look at the torque curve and you will understand what I am talking about. Also, swapping that complete FI computer controlled motor involves all the wiring too, its a LOT of work unless you are really prepared to undertake such a thing. But yes, best of both worlds is a 258 with a 4.0 head, but a lot more work than just rebuilding your 258, it all depends on how much you want to spend and how much time you have. And yes, I have experience with both sixes, the Cherokee I drive for work has the 4.0 and my CJ has a 258, I love the 4.0 for the street but would much rather have a 258 for off road.

Brad
ORC Land Use Editor

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