Had issues with a few pistons in different motors getting scuffed , one issue was bottom of cylinder bore was'nt de-burred , the other was a tight gudgeon pin............ran .007" piston to bore clearance on the 605" , these Ross pistons would scuff pretty bad , never thought it to be the manu fault , those pistons hung out the bottom of bore & rocked like crazy , don't think any film of oil would of helped those pistons.