360 conecting rod play

I just had a caddy 500 waste it's upper rod bearings due to detonation. My machinist told me that detonation put an extra load on the rod bearings(tops) and they wore down to the copper.....that was in 35 miles. My customer is to blame for this. He had someone adjust timing and carb AFTER my shop. It also broke 2 ring landings off.