Illus 75 Removing Piston Rings

rings—.005", .010", .020", .030", .040", .050", .060" and .070".

Special type oil control rings—.005", .010", .020", .030" and .040".

Piston rings must have proper side clearance in ring grooves. In new assembly, this is .004". Check with thickness gauge as shown in Illus. 76. Maximum permissible side clearance is .008".

Standard ring gap between ends of rings when inserted squarely in cylinder bore is .010" to .020".

To check piston ring gap place a piston in cylinder with top end of piston about V2" from top end of cylinder as shown in Illus. 77. Set the ring to be checked in cylinder bore squarely against piston. With a thickness gauge check ring gap as shown in Illus. 77. Even though ring gap may be slightly greater than standard, only standard size piston rings should be used in cylinder unless cylinder has been refinished oversize.

If cylinder has been refinished oversize, then use the correct oversize rings, fitting rings to give standard gap.

If gap is less than .010", ring ends may butt under expansion, and rings may be scored or broken. Gap may be increased by filing with a fine-cut file.

When installing piston rings be sure compression rings and oil control rings are placed in their proper grooves.

Use thin strips of metal to guide and slip rings over the piston into their respective grooves without overexpanding or twisting rings and damaging the finely finished piston surface. See Illus. 75. Thin strips can also be used to good advantage when removing piston rings.

Note: Examine rings to determine if "TOP" is stamped on one side. If so, install ring with "TOP" upward.

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