I have a h22a4 with what I think is a spun rod bearing. I pulled off the oil pan and there is a little play on cylinder 1 and no play on any of the others. Is it possible to replace the bearing without pulling the block and is there any way to check the clearance to see what oversized bearing I would need?

 

It would be really hard plastigauging without pulling the motor. You plastigauge in order to check the clearances and depending what you get, decide which bearing you'd need.

 

Check the oil pan and pick-up for bearing backing bits. All of that stuff needs to be cleaned out before it goes back on the engine.

The good news is that you might not have spun the bearing. The bearing might be worn into the backing and broken, and the crank might only have minimal damage.

The bad news is that the rod might have been heat stressed and might need to be replaced. You should also have the rod journal polished, if possible, to remove any of the scoring on the journal.