We finally hurt an engine (408) last year and something hit the block so I'm assuming a rod broke but it's not apart yet for me to see. This was a K1crank and K1 rods with upgraded bolts which I always do. It was rebuilt 3 times and in need of its 4th when my son asked to borrow it and finally let go. I particularly blame running alcohol as it's harder on bearing, bore wear, and other issues.