Piston Ring Clearance

Courtesy of GENERAL MOTORS COMPANY

Install the piston rings to the cylinder (1) and measure the piston ring end gap. Compare the measurements with those provided below:
1. The upper compression ring end gap. Place the piston ring in the area of the bore where the piston ring will travel approximately 10 mm (0.4 in) down from the deck surface. Refer to ENGINE MECHANICAL SPECIFICATIONS for the correct value of the clearance.
2. The lower compression ring end gap. Place the piston ring in the area of the bore where the piston ring will travel approximately 18 mm (0.7 in) down from the deck surface. Refer to ENGINE MECHANICAL SPECIFICATIONS for the correct value of the clearance.
3. The oil scraper ring end gap. Place the piston ring in the area of the bore where the piston ring will travel approximately 23 mm (0.9 in) down from the deck surface. Refer to ENGINE MECHANICAL SPECIFICATIONS for the correct value of the clearance.
If the clearance is greater than the provided specifications, the piston rings must be replaced.
Courtesy of GENERAL MOTORS COMPANY

Measure the piston ring axial clearance (1). Compare the measurements with those provided below:
1. The upper compression ring end gap. Refer to ENGINE MECHANICAL SPECIFICATIONS for the correct value of the clearance.
2. The lower compression ring end gap. Refer to ENGINE MECHANICAL SPECIFICATIONS for the correct value of the clearance.
3. The oil scraper ring end gap. Refer to ENGINE MECHANICAL SPECIFICATIONS for the correct value of the clearance.
If the clearance is greater than the provided specifications, replace the piston rings.
If the clearance is still to great, replace the pistons.