lawsoncl said:
Rod bearings you need to pull the head which is a lot of work....
Huh? Why can't you just pull the spark plugs, turn the crank so the piston being worked on is BDC, unbolt the rod cap and push the piston up an inch or two? Just swap out the bearing and pull them back together?
If the piston is too stuborn to push yourself, you can turn the crank to 90° position, for the piston being worked on, unbolt the cap and turn the crank to BDC, leaving the piston behind (about mid-stroke) and pulling the crank away from the rod, giving you access to the journals.
If your just swapping the bearings, it can be done in a weekend, if you find the crank is bad, well, thats going to take a lot longer. The bearings are cheap enough, I'd probably put them in anyway and hope for the best, if it doesn't work, then you'll just back where you started.
Look the crank over for any knicks in the surfaces. If a knicked raised the surface of the edges higher than the rest of the crank journal you can rub that down with some emory cloth.
If the crank journals are all worn down and groovey/wavey, theres nothing you can do add metal to the journal, maybe new bearing will reduce the clearance enough that the motor will run with a little higher oil pressure and no knock. But if you want to properly fix it, you have to pull the crank and have it turned down and then get over sized bearings. You might as well pull the engine and do a rebuild if your going to do that.