[ashes29]

I am currently fixing an engine knock in a friends car(same engine as in my profile), and after removing the rag I found jammed in the throttle body(previous shop it was at sucked hard) i removed the head and piston #4 is hitting the head, not enough to dent or scuff either but enough to keep the high spots on the piston and the corresponding spot on the head shiny. Any ideas on what could be causing this? I don't want to tear down more than i have to. also the bearing on the #4 rod was the work done at the previous shop...i have been told that if they reversed the rod it could make it do this.....thanks

i have thoroughly gone over the head and everything is fine there, no bent valves, head gasket was good, mating surface is not warped