[Doobletango]

I have an Allis Chalmers D17 that has a spun rod bearing. My manual says standard crank journal should be 2.995. I have 2.36. I double checked another journal and have 2.36 as well. How do I size the bearings? I’m used to small engines where you grind the crank journal and get an undersized rod. I’m guessing I need .030” bearings?

 

[Ultradog]

Yes.
Your crank has been ground before. How much undersized they can grind the journals varies from engine to engine. My Fords can go down to .040 undersized but that is not the case with every engine.
If your crank is already .030 under and that journal is damaged I would start looking for bearings and/or talk to a machine shop before you go any further with this project.