Is there a simple way I can tell if my car needs over or undersized con rod bearings? Or even standard? Also are they interchangeable? As in if oversized were being used can I buy a set of undersized and expect it to work fine or at least not have to worry about it destroying my journal? I spun my last ones or at least the first 2 were definitely at the point of no return while bearings on piston 4,2 were fine still having a operable tongue with no deformation. Main question would just be if they were interchangeable so I can go ahead and just buy a couple sets or if they arent able to be mixed can I buy a set and just change them all. The journal has never been machined. The journal is still to my knowledge in good shape. Has a shine to it with very small scratches on the ones that spun but almost trivial enough they couldn't be seen... Since im here also same question for piston rings. I broke a set trying to remove one and did not realize they have the same size types and there isnt just a single one to pick from. Thanks

 

If the crank has never been machined then standard should be fine. Only real way to know is to measure the journals and rods/mains with a micrometer, or alternatively use plastigage. For a stock rebuild as long as the rod bearing clearances are between .001 and .002", you're good. The mains are a little different though because each one requires slightly different clearances with the largest being in the center. All you can really do is measure and order accordingly. If you're not comfortable doing that then take it to a local machine shop and they will tell you what you need. You may consider having them micropolish it to remove any small scratches while it's there.

If you get the sizing wrong you will quickly spin a bearing or have knock/low oil pressure. It's imperative that it be somewhere in the acceptable range.