reusing new rod/main bearings

I have 2 complete 4.0's, 1 in my truck & running, the other halfway built (short block). I've lost my dry & warm repair space, & would now like to quickly swap the new rod/main bearings that I just installed in the builder into the running engine via the oil pan. I built a quick & dirty but complete short block, so obviously the crank & rods/pistons have been rotated while being installed & plastiguaged. Unfortunantely, most clearances are not in spec. Willl these bearings still have their manufactured dimensions or do you suppose they are now crushed & useless for the runner?

If they were lubed with assembly lube or heavy motor oil, they should be okay, but why weren't tey in spec in the short block? If they didn't work in one engine, they may not work in the "runner."

Check the codes stamped into the passnger side of the block, near the distributor. In addition to the build date, if the factory went oversize on cylinder bore and/or undersize on road and/or main bearings, there will be a letter code to indicate this.

Unless you know that the same size is required in the runner as your builder, the bearings may have been useless from the beginning. The size bearings used within Jeep engines were not necessarily uniform between engines, even of the same model year. Your runner and builder may need different sized bearings. Assuming the bearings required for both engines are the same size, as long as there is no real scoring of the bearing surfaces, I should think that swapping them from your builder into your runner would be ok.

I replaced the rod & main bearings in my 88 last winter. I was really surprised to see the range of bearing tolerances and color coding used by Jeep as listed in the manual. I ended up replacing the engine with a reman (bearings weren't the real problem), and have kept the old one to possibly rebuild one day.

When I disassembled the motor to rebuild it the crank seemed fine & measurements of the journals seemed OK. The old bearings weren't under/oversize & there was also no stamping to indicate this. The journals seemed pretty smooth as well. With new bearings & then Plastiguage, however, show journal taper. I had hoped I wouldn't need machine work, so I shelved the rebuild project until I could afford to go whole hog. Very recently I've decided to move and will need my running Jeep to make it on a 1200 mile trip, & now I'm starting to develop very fine shavings on the oil dipstick. This seems to be bearing debris, so I'm hoping to drop the pan, swap bearings and seals from the aborted rebuild, and be on my way w/o having to buy another set of mains/rods. i suppose before I commit I will pull the new bearings and eyeball 'em.