6627030 3-5/16" piston rings. +.030"

These Hastings rings are built for the 3-5/16 inch bore found on 1937 to 1948 74-inch U-model Flatheads and 1948 to 1952 61-inch E or EL Panheads, but sized for a .030 inch oversize. The kit features 3/32 inch parkerized compression rings and 3/16 inch chromed three-piece oil rings. When you're boring out an old cylinder, you need rings that can handle the heat and provide a consistent seal. Hastings uses a low-tension flex-vent design for the oil rings which is perfect for these older configurations. Always verify your piston groove dimensions during the mock-up phase to ensure these rings seat properly for a long-lasting engine life.