MODIFIED OIL RAILS
When file fitting rings I also like to add a radius to the backside of the oil ring support rails, at the gap. I rough in the radius on the belt sander and then finish it on the debur wheel on my ring grinder. Without adding this radius to the support rails, I noticed that the rails would dig into the back of the ringland in the piston.

Nick Jones
Automotive Machine
Fraser, MI
June, 2019