I am in the middle of doing a 4.0 swap into mt 81 cj5. I have the 4.0 on a motor stand and had plans of rebuilding it. I have it all tore down and was looking in the cylinders. I can still see the factory cross hatching on the cylinder walls. all the rod bearing dont have any play in them. should I rebuild it anyway just to be safe? the donor cherokee had 160,000 miles and ran fine. I dont want to do the stroker yet im just getting the 4.0 in and ready to go for the summer. Maybe take my time and build a stroker while I can still run the jeep. any thoughts? advice?
just roll in a new set of rod and main bearings and put some new rings in it. You can check the cylenders to see if they are ovaled out, if they are not an are withing spec then it doesn't need to be bored just run a hone through it.
When I had my AMC 360 rebuilt the pistons had .020 stamped on the top. Also.. the back of the bearings are date stamped. If I were you I'd take it to a machine shop while you have it out of the vehicle and have them hot tank it and check it over. That way if it is in great shape you'll know for sure and if something needs to be done they can do it.
upload them to phtobucket the copy the direct address link. come here and click on the little mountain post card looking thing on the toolbar of the message box and paste the address into the box that pops up
That cross hatching looks pretty deep.. maybe done by hand with one of those power drill dealies.
If you don't want to dump a ton of cash in it.. just do a "poor man's rebuild" by replacing all the gaskets. Did you take a look at the back of the bearings to see if the year matches the year of the vehicle?
I still vote for a machine shop drop off just for a hot tanking and inspection... It would suck to get everything back in the vehicle after all that work (and a spendy gasket kit) for it to crap out after a few thousand miles. Tell them this is a mega budget motor and they will only do the things that ABSOLUTELY need to be done.. if anything.
If it was recently machined then at least you'll know that it's still in spec. I mean we are only talking maybe $100 for the hot tank + inspection.