8M0049920 Mercury TOP COWL ASSEMBLY, Mariner 30-40hp, w-o decals

Illustration 1 g00294082 (1) Valve springs Length of the valve springs under test force ... 39.0 mm (1.54 inch)Test force of the valve springs. ... 246 to 277.5 N (55 to 62 lb) (2) Valve spring recess (3) Valve guides Partially finished valve guide ... 8.600 mm to 8.700 mm (0.3386 inch to 0.3425 inch)Inside diameter of finished valve guide ... 9.000 to 9.022 mm (0.3543 to 0.3552 inch)Outside diameter of the inlet valve guide ... 13.034 to 13.047 mm (0.5131 to 0.5137 inch)Outside diameter of exhaust valve guide ... 14.034 to 14.047 mm (0.5525 to 0.5530 inch)Bore diameter in the cylinder head for the inlet valve guide ... 13.00 to 13.03 mm (0.512 to 0.513 inch)Bore diameter in the cylinder head for the exhaust valve guide ... 14.000 to 14.027 mm (0.5512 to 0.5522 inch)Overall length of inlet and exhaust valve guides ... 51.25 mm (2.012 inch)Projection of the valve guide above the valve spring recess (2) ... 14.85 to 15.15 mm (0.585 to 0.596 inch)Note: When new valve guides are installed, new valves and new valve seat inserts must be installed. The valve guides and the valve seat inserts are supplied as partially finished parts. The unfinished valve guides and unfinished valve seat inserts are installed in the cylinder head. Then, the guides and inserts are cut and reamed in one operation with special tooling. This procedure ensures the concentricity of the valve seat to the valve guide in order to create a seal that is tight. Refer to the Disassembly and Assembly Manual for removal and installation procedures. (4) Exhaust valve stem Diameter of the exhaust valve stem ... 8.938 to 8.960 mm (0.3525 to 0.3533 inch)Clearance of exhaust valve in valve guide ... 0.040 to 0.084 mm (0.0016 to 0.0033 inch)Overall length of the exhaust valve ... 122.65 to 123.30 mm (4.829 to 4.854 inch) (5) Inlet valve stem Diameter of the inlet valve stem ... 8.953 to 8.975 mm (0.3525 to 0.3533 inch)Clearance of inlet valve in valve guide ... 0.025 to 0.069 mm (0.0010 to 0.0027 inch)Overall length of the inlet valve ... 122.65 to 123.30 mm (4.829 to 4.854 inch) (6) Exhaust valve face angle Valve face angle ... 45 degreesValve seat angle ... 46 degrees (7) Exhaust valve head diameter ... 40.88 to 41.12 mm (1.60945 to 1.61889 inch)Exhaust valve depth below the cylinder head face Minimum ... 1.50 mm (0.059 inch)Maximum ... 1.80 mm (0.071 inch)Service limit ... 2.05 mm (0.081 inch) (8) Diameter of the head of the inlet valve ... 42.88 to 43.12 mm (1.688 to 1.698 inch)Depth between the inlet valve and the cylinder head face Minimum ... 1.40 mm (0.055 inch)Maximum ... 1.70 mm (0.0669 inch)Service limit ... 1.95 mm (0.0768 inch) (9) Angle of the face of the inlet valve Valve face angle ... 30 degreesValve seat angle ... 31 degreesThe valve lash is the following value when the engine is hot or cold: Inlet valves ... 0.20 mm (0.008 inch)Exhaust valves ... 0.45 mm (0.018 inch)
Illustration 2 g00840529 (10) Machine the recess in the head for valve seat inserts to the following dimensions. Inlet valve (A) ... 10.585 to 10.715 mm (0.4167 to 0.4219 inch) (B) ... 45.535 to 45.560 mm (1.7927 to 1.7937 inch) (C) Maximum radius ... 0.38 mm (0.015 inch)Exhaust valve (A) ... 10.585 to 10.715 mm (0.4167 to 0.4219 inch) (B) ... 43.535 to 43.560 mm (1.7140 to 1.7150 inch) (C) Maximum radius ... 0.38 mm (0.015 inch)
Illustration 3 g00840530 (11) Valve seat insert Inlet valve (D) Included angle of the faces of the valve seat insert ... 118 degrees (E) Horizontal dimension of the chamfer ... 0.38 mm (0.015 inch) (F) Vertical dimension of the chamfer ... 0.38 mm (0.015 inch)Exhaust valve (D) Included angle of the faces of the valve seat insert ... 88 degrees (E) Horizontal dimension of the chamfer ... 0.38 mm (0.015 inch) (F) Vertical dimension of the chamfer ... 0.38 mm (0.015 inch)