Mitsubishi 4G1 Service Manual page 223

Side rail gap
1 EN026
(8) Check that the piston moves smoothly.
OIL RING INSTALLATION
(1) Fit the oil ring spacer into the piston ring groove.
NOTE
The side rails and spacer may be installed in either direction.
(2) Install the upper side rail.
To install the side rail, first fit one end of the rail into the
piston groove, then press the remaining portion into
position by finger. See illustration.
Caution
Do not use piston ring expander when installing side
rail.
(3) Install the lower side rail in the same procedure as
described in step (2).
(4) Make sure that the side rails move smoothly in either
direction.
STALLATION
(1) Using a piston ring expander, fit No. 2 and then No. 1 piston
ring into position.
NOTE
(1) Note the difference in shape between No. 1 and No. 2
piston rings.
(2) Install piston rings No. 1 and No. 2 with their side having
marks facing up (on the piston crown side).
Revision