You might want to first ID the engine, so that you can then look at a Shop Manual for information on how to inspect the rod and main bearings (
several Shop manuals are on-line here ).
Post the codes and people will help you with IDs. Also, follow Hotrod Lincoln's advice (above) for IDing a low-pressure vs a high-pressure engine. Once that has been done, people can give better advice regarding bearing inspection and clearances.
