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Unread 07-31-2005, 10:37 PM   #1
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Join Date: Jan 2005
Posts: 69
Worth keeping or swap?

I have a '79 CJ7 with the original 258 engine (~125k miles), and as far as I know, no serious work done on it. I was fine with the 258 and am working on getting it running good, but I planned to swap in a 304 or 360 if it ever died. Now I am beginning to wonder if it is worth it to work on the 258. The engine bay looks like a small war was fought there, there are random disconnected parts all over the place, 60% of the tubes lead nowhere and all sorts of engine bay horror stories. You have to run 20W50 oil to keep the pressure high enough to register on the gauge and only runs on a straight carb (no air filter.) Often the engine will idle ok, but if you load it at all, like to inch forward, it will instantly die. I have already put the works in motion to put a MC2100 on there, but testing it a little I noticed a few more things. There is a tapping under the valve cover, probably a lifter. Also, it seems like at least 2 cylinders arn't firing or are missing under load. The weirdest part will be the random changes in the performance. After I was working on the PS system, I got it running and it sounded and idled ok (didn't try to move it), then I tried a few days later (changing nothing) and it was like crap (barely started, sounded sporatic, had to keep RPMs up for it not to die). I am just imagining all the money and work I will have to put into this engine I don't know the history of to get it running "right" and hope it doesn't blow up in a month or something. The only way a swap would be feasible is if it was < $1000, which I know is a BIG stretch on any account. If I can't get this engine working or a new one, this Jeep will have to be a lawn ornament for the next couple years. Thanks for any input!

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Unread 08-07-2005, 12:46 PM   #2
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Join Date: Jun 2005
Location: SW Florida, from Ohio
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I wouldnt put alot of money into an engine that old with that many issues. Good engines but if it was mine Id swap in somthing different. Ive seen lots of used 5.0 fords around that are pretty cheap. Only seen a yj with that conversion. A carburated 360 would be nice.
'94 Yj, 4.0, 5 spd manual.
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Unread 08-07-2005, 10:08 PM   #3
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1971 CJ5 
Join Date: Jan 2002
Location: Eagle Point, Oregon
Posts: 6,750
One thing to remember is a multitude of little things can add up to one big thing. First thing you need to do is purchase a good Chilton or other service manual and do some basic troubleshooting. You might find that the engine is basicly sound, and that some simple adjustments and tuneup parts can go a long way. The knowledge you garner out of this exercise will follow you through your later Jeep years.
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Unread 08-08-2005, 09:37 AM   #4
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I have a Haynes manual, but it isn't that great. I look at it and look at my Jeep and get . It is one of those "general" manuals that says it covers every CJ ever made, but it only has like 4 pages dedicated to my engine. I am gonna get a Chiltons. The 360 is what I am really hoping for, I hope with gas prices going up I can find one for cheap . As for right now, I will probably do the MC2100, and try to clean it up a bit. Signs are starting to point towards an electrical problem now, probably needs a new distributor or something. If I can't get it running ok with the MC2100 and minor work I will probably park it for a while until I get some funds.

On a side note, does anyone know why it will idle but won't move? Like I said before, sometimes it will idle ok in neutral, but if you try to move, as soon as the engine sees a load, it will just die. That is the main thing right now, because I can't even drive it like that, and its pissing me off . Thanks for your thoughts!
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