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Jeep Wrangler YJ
YJ General Discussion
Time to rebuild my 258 /4.2 engine and I'm wondering those of you here who have done it what would you do again what not to bother with?
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<blockquote data-quote="ytradio" data-source="post: 434441" data-attributes="member: 19779"><p>The way you say that you are going to use your YJ, I personally would not go out of my way to get the 4.0 head. If you have access to one and it will save you money over rebuilding the 258 head fine, but the performance gain will be at higher rpm not low end torque. I am in the process of rebuilding my 89 and I have studied quite a bit of torque and horsepower curves on different builds, and unless you are planning on winding the rpm’ s up. I feel it is just money wasted. I am reconditioning the crank with new main and rod bearings, probably end up boring 10 over with new pistons, rings and pins. New rod bolts, plane the 258 head for flatness, and do a valve job, maybe new valves not sure if needed.</p></blockquote><p></p>
[QUOTE="ytradio, post: 434441, member: 19779"] The way you say that you are going to use your YJ, I personally would not go out of my way to get the 4.0 head. If you have access to one and it will save you money over rebuilding the 258 head fine, but the performance gain will be at higher rpm not low end torque. I am in the process of rebuilding my 89 and I have studied quite a bit of torque and horsepower curves on different builds, and unless you are planning on winding the rpm’ s up. I feel it is just money wasted. I am reconditioning the crank with new main and rod bearings, probably end up boring 10 over with new pistons, rings and pins. New rod bolts, plane the 258 head for flatness, and do a valve job, maybe new valves not sure if needed. [/QUOTE]
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Jeep Wrangler YJ
YJ General Discussion
Time to rebuild my 258 /4.2 engine and I'm wondering those of you here who have done it what would you do again what not to bother with?
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