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post #1 of (permalink) Old 02-26-2002, 02:33 PM
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Looking for 1 Piston!

Hallalooya! I thought I was ready to put the MPI from a wrecked 95 on the CJ 258 with a significantly modified 4.0 head.

The mechanic who was to replace the piston that I burnt a hole in after 5,000 miles called and said he could not find a single piston that would work in the 258! So, it seems the saga of challenges have only increased. My question is...can I just replace a single piston or do I need to get a complete set - everything was new 5,000 miles ago (pistons, rings, rods, etc). Mechanic tells me there was not scoring on the cylinder walls and that honing should smooth it up. If buying a single piston will work, then recommendation on best parts source for this?

If not, then I have a more complex issue. I do have the bottom end from a 1990 Cherokee that I could rebuild using the crank from the 258 and then mount the 95 MPI and modified 95 4.0 head to the 90 4.0 block. I understand that stoking the engine will also then require significant modifications to the computer and the injectors. Even rebuilding it with the 4.0 lower end and mating it to he 999 tranny and d300 transfer case seems to be getting more complex and expensive.

Mindbender 85CJ7 I258 [img]/wwwthreads_images/icons/smile.gif[/img] 40 head ported polished [img]/wwwthreads_images/icons/smile.gif[/img]
Jacobs [img]/wwwthreads_images/icons/smile.gif[/img] 31" [img]/wwwthreads_images/icons/smile.gif[/img] 999 insulated hard top
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post #2 of (permalink) Old 02-26-2002, 02:45 PM
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Re: Looking for 1 Piston!

personally I would get the set of 6 pistions and just replace them. the pistions should be cheap as well as the rings. pop them off the conecting rod and replace.

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post #3 of (permalink) Old 02-26-2002, 09:59 PM
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Re: Looking for 1 Piston!

You didn't mention what size piston you have(std, .030, .040, .060). Most any parts store should be able to get one in two days. Try online. Napa, zone, advance, carquest etc should have them readily available. If he is concerned with brand name, ALL oem replacements are the same weight and same basic configuration. Compression should be the same also(year specific).


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post #4 of (permalink) Old 02-26-2002, 11:49 PM
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Re: Looking for 1 Piston!

You should be able to get one piston...just be SURE it is EXACTLY the same (same weight) as the other five. If you get a piston from the same mfg. as the other ones it should be good enough, but if you have five Ross pistons and one TRW it will be out of balance enough to shake the bottom end apart. I know it is not a race motor, but differences in manufacturing from brand to brand is significant enough to make it an issue.

Mike H.
1983 CJ-7 Laredo, 1991 Cherokee Ltd.
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