Acura NSX 1991 Manual page 140

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Piston Rings
End Gap
1. Using a piston, push a new ring into the cylinder
bore 15 - 20 mm (0.6 - 0.8 in) from the bottom.
2. Measure the piston ring end-gap with a feeler
gauge:
• If the gap is too small, check to see if you have
the proper rings for your engine.
• If the gap is too large, recheck the cylinder bore
diameter against the wear limits on page 7-12. If
the bore is over limit, the cylinder block must be
rebored.
Piston Ring End-Gap:
Top Ring
Standard (New): 0.25-0.40 mm
Service Limit:
Second Ring
Standard (New): 0.35-0.50 mm
Service Limit
Oil Ring
Standard (New): 0.20-0.70 mm (0.008-0.028
Service Limit:
Table of Contents
(0.010-0.016 in)
0.60 mm (0.024 in)
(0.014-0.020 in)
0.75 mm (0.03 in)
in)
0.80 mm (0.031 in)
Replacement
1. Using a ring expander, remove the old piston rings.
2. Clean all ring grooves thoroughly.
NOTE:
• Use a squared-off broken ring or ring groove
cleaner with blade to fit piston grooves.
• Top and 2nd ring grooves are 1.2 mm (0.05 in)
wide and the oil ring groove is 2.8 mm (0.11 in)
wide.
• File down the blade if necessary.
CAUTION: Do not use a wire brush to clean the ring
grooves, or cut ring grooves deeper with a cleaning
tool.
3. Install new rings in the proper sequence and posi-
tion (see page 7-16).
NOTE: Do not reuse old piston rings.