GMC Workshop Service and Repair Manuals

Piston: Specifications

Piston Ring End Gap - Measured in Cylinder Bore
First Compression Ring
Production .....................................................................................................................................................................  0.23 - 0.44 mm (0.009 - 0.017 inch)
Service ...........................................................................................................................................................................  0.23 - 0.5 mm (0.009 - 0.0196 inch)

Second Compression Ring
Production .......................................................................................................................................................................  0.44 - 0.7 mm (0.017 - 0.027 inch)
Service ...........................................................................................................................................................................  0.44 - 0.76 mm (0.0173 - 0.03 inch)

Oil Control Ring
Production .....................................................................................................................................................................  0.18 - 0.75 mm (0.007 - 0.029 inch)
Service ...........................................................................................................................................................................  0.18 - 0.81 mm (0.007 - 0.032 inch)

Piston Ring to Groove Clearance
First Compression Ring
Production ...........................................................................................................................................................  0.04 - 0.085 mm (0.00157 - 0.00335 inch)
Service .................................................................................................................................................................  0.04 - 0.085 mm (0.00157 - 0.00335 inch)

Second Compression Ring
Production .............................................................................................................................................................  0.04 - 0.078 mm (0.00157 - 0.0031 inch)
Service ...................................................................................................................................................................  0.04 - 0.078 mm (0.00157 - 0.0031 inch)

Oil Control Ring
Production .................................................................................................................................................................  0.012 - 0.2 mm (0.0005 - 0.0078 inch)
Service .......................................................................................................................................................................  0.012 - 0.2 mm (0.0005 - 0.0078 inch)

Piston Diameter .......................................................................................................................................................  96.002 - 96.036 mm (3.779 - 3.78 inch)
(Measured Over Skirt Coating)

Piston to Bore Clearance
Production ........................................................................................................................................................  0.036 to 0.016 mm (-0.0014 to 0.0006 inch)
Service Limit with Skirt Coating Worn Off .....................................................................................................................................  0.071 mm (0.0028 inch)

Piston Pin Fit in Connecting Rod Bore ...............................................................................................................  0.02 - 0.043 mm (0.00078 - 0.00169 inch)

Piston Pin Clearance to Piston Pin Bore
Production ...........................................................................................................................................................  0.007 - 0.02 mm (0.00027 - 0.00078 inch)
Service ...............................................................................................................................................................  0.007 - 0.021 mm (0.00027 - 0.00082 inch)

Piston Pin Diameter ...............................................................................................................................................  23.997 - 24.0 mm (0.9447 - 0.9448 inch)