Low Tension 68mm Standard Piston Rings
AKRA 2020 Rules for Rings
Top ring and middle ring .115" max-width, .060" max thickness.) Filing of ring end gaps permitted including oil expander, max end gap .040" (top rings only.) The lapping of rings permitted for proper seal. Piston Ring must be on the piece (unbroken) when presented for tech. Piston Rings must be self-supporting in the cylinder bore when checked installed on the piston with a connecting rod attached (rod cap and bolts installed are not required for this check).
NKA 2020 Rules for Rings:
40.4.13: Piston Rings
40.4.13.1: It is mandatory that all three rings be intact and functional.
40.4.13.2: Top ring must be the chrome face ring
40.4.13.3: No alterations of rings are permitted.
40.4.13.4: Ring Sizes
Top Ring
.058" +/-.005" height & .115" maximum width.
Middle Ring
.058" +/-.005" height & .115" maximum width.
Oil Expander Ring (reference)
.095" +/-.005" height & .092" +/-.005" width
40.4.14: Ring Tension Requirement
Top two rings must support themselves in the cylinder when removed from the piston. They cannot fall through the cylinder.
Bottom ring is a non-tech item regarding tension. Bottom expander ring & two rail rings, when mounted on piston and rod in place should support the piston in
the cylinder when inserted upside-down.
40.4.15: Ring Tension Inspection Procedure
Top 2 rings must support themselves without assistance in the cylinder.
Each of the top two rings should be placed, individually, approx. one inch
(1") down in the cylinder.
Square ring with piston turned upside down.
If ring supports itself it is legal.
