881633 Mercruiser GASKET SET, Intake Manifold and Valley

Illustration 1 g01363510
Typical example
(1) Top compression ringNaturally AspiratedThe shape of the top compression ring ... Rectangular with a barrel faceWidth of the top compression ring ... 2.47 to 2.49 mm (0.0972 to 0.0980 inch)Clearance between the top compression ring and the piston groove ... 0.09 to 0.13 mm (0.0035 to 0.0051 inch)Ring gap ... 0.30 to 0.55 mm (0.0118 to 0.0217 inch)TurbochargedThe shape of the top compression ring ... Keystone with a barrel faceWidth of the top compression ring ... taperedRing gap ... 0.30 to 0.45 mm (0.0118 to 0.0177 inch)Note: When you install a new top compression ring, make sure that the word "TOP" is facing the top of the piston. New top piston rings for naturally aspirated engines have a red identification mark which must be on the left of the ring end gap when the top piston ring is installed on an upright piston. New top piston rings for turbocharged engines have a yellow identification mark which must be on the left of the ring end gap when the top piston ring is installed on an upright piston. (2) Intermediate compression ringThe shape of the intermediate compression ring ... Internal chamfer in the bottom edge with a tapered faceWidth of intermediate compression ring for naturally aspirated engines ... 2.47 to 2.49 mm (0.097 to 0.098 inch)Width of intermediate compression ring for turbocharged engines ... 2.470 to 2.495 mm (0.0972 to 0.0982 inch)Clearance between the intermediate compression ring and the piston groove for naturally aspirated engines ... 0.05 to 0.09 mm (0.002 to 0.003 inch)Clearance between the intermediate compression ring and the piston groove for turbocharged engines ... 0.065 to 0.110 mm (0.0026 to 0.0043 inch)Ring gap for naturally aspirated engines ... 0.70 to 0.95 mm (0.0275 to 0.0374 inch)Ring gap for turbocharged engines ... 0.75 to 1.25 mm (0.0295 to 0.0492 inch)Note: When you install a new intermediate compression ring, make sure that the word "TOP" is facing the top of the piston. New intermediate rings for naturally aspirated engines have a green identification mark which must be on the left of the ring end gap when the top piston ring is installed on an upright piston. New intermediate rings for turbocharged engines have a blue identification mark which must be on the left of the ring end gap when the top piston ring is installed on an upright piston. (3) Oil control ringShape of oil control ring ... a two-piece coil that is spring loadedWidth of oil control ring for naturally aspirated engines ... 3.47 to 3.49 mm (0.1366 to 0.1374 inch)Width of oil control ring for turbocharged engines ... 2.97 to 2.99 mm (0.1169 to 0.1177 inch)Clearance between the oil control ring and the groove in the piston for naturally aspirated engines ... 0.03 to 0.07 mm (0.0011 to 0.0027 inch)Ring gap ... 0.30 to 0.55 mm (0.0118 to 0.0216 inch)Note: A pin is used in order to hold both ends of the spring of the oil control ring in position. The ends of the spring of the oil control ring must be installed opposite the end gap of the oil control ring.Note: Ensure that the ring end gaps of the piston rings are spaced 120 degrees from each other.Piston
Note: An arrow which is marked on the piston crown must be toward the front of the engine.The combustion bowl re-entrant angle for the turbocharged engine ... 72 degreesThe combustion bowl re-entrant angle for the naturally aspirated engine ... 70 degreesPiston height above cylinder block ... 0.21 to 0.35 mm (0.008 to 0.014 inch)Width of top groove in piston for the naturally aspirated engine ... 2.58 to 2.60 mm (0.1016 to 0.1024 inch)Width of top groove in piston for the turbocharged engine ... TaperedWidth of second groove in piston for naturally aspirated engines ... 2.54 to 2.56 mm (0.1000 to 0.1008 inch)Width of second groove in piston for turbocharged engines ... 2.56 to 2.58 mm (0.1008 to 0.1016 inch)Width of third groove in piston for naturally aspirated engines ... 3.52 to 3.54 mm (0.1386 to 0.1394 inch)Width of third groove in piston for turbocharged engines ... 3.02 to 3.04 mm (0.1189 to 0.1197 inch)Piston pinDiameter of a new piston pin ... 39.694 to 39.700 mm (1.5628 to 1.5630 inch)Diameter of the bore for the piston pin ... 39.703 to 39.709 mm (1.5631 to 1.5633 inch)