Being two years ago probly no warrnty left if you got one,so pull the heads and see if you have a clerance issue,I had one that sounded like colapsed lifters ticking just went with .040compressed thicker head gasket.thats if valve is hitting piston ,not piston hitting head like Pat said.you'v made some runs on it so you will see what's hitting for sure.if that checks out could it be a froze up rist pin from setting Pat?.