REALLY clean out the case. Paint brushes and parafin, rags, and blow it out with an airline (with eye protection..easy to forget). When I had to chisle the liners out of my engine block I wrapped everythig in clingfilm but still bits got stuck. I spent several hours doing nothing but washing and air blasting every crevice in the block. At the first oil change I ran a magnet probe around the sump, not a single chip. Its worth putting a lot of effort into getitng it free of debris.