Its pretty simple, really. There will be some restriction if you run them tight. But guys run them with far more than what will provide any restriction what so ever. If you have a .003 bearing clearance, then .003 extra(or slightly more) side clearance will give you as much room for the oil to escape as a larger clearance will. With folks running them very loose as with stock width BBC rods on stock width mopar journals, it must be apparent that the increase in oil flow isn't enough for most of us to worry about. It probably will show up on a dyno, but I wouldn't want to spend the time or money figuring out how close i could run them before disaster strikes. It would probably come from bind between rods, not an oiling issue.