Piston Ring, Engine

Piston Ring-To-Groove Clearance
Compression (top) 0.040-0.075 mm (0.0015-0.0029 in.)
Compression (bottom) 0.040-0.085 mm (0.0015-0.0033 in.)
Oil ring Snug Fit
Piston ring gap f
Compression (top)-gauge diameter 0.100-0.250 mm (0.0039-0.0098 in.)
Compression (bottom)-gauge diameter 0.27-0.42 mm (0.0106-0.0165 in.)
Oil ring (steel rail)-gauge diameter 0.15-0.65 mm (0.0059-0.0255 in.)
Compression (top)-service limit 0.50 mm (0.0196 in.) max.
Compression (bottom)-service limit 0.65 mm (0.0255 in.) max.
Oil ring (steel rail)-service limit 0.90 mm (0.0354 in.) max.
Ring groove width
Compression (top) 1.230-1.245 mm (0.0484-0.0490 in.)
Compression (bottom) 1.530-1.545 mm (0.0602-0.0608 in.)
Oil ring 3.030-3.055 mm (0.1192-0.0120 in.)

f Specification 82.4 mm (3.2441 in.) diameter gauge