816742 Mercruiser SCREW, (.250-20 x 1.250)

Illustration 1 g06390284
Front view
Illustration 2 g06386425
Right side view
Table 1
Item Qty Part Specification Description
During assembly, the bottom of spacer plates, top of cylinder block and both sides of plate gasket must be free of fuel, oil, water, gasket adhesives, assembly compounds and any other contaminants.
D1 16 - Thickness is 12.313 mm (0.4848 inch).
D2 - - Extension of the dowel from the top face of the cylinder block 21.0 0.5 mm (0.83 0.02 inch).
D3 16 - Thickness of the plate gasket between the cylinder block and spacer plate 0.194 to 0.218 mm (0.0076 to 0.0086 inch).
1 4 - Torque to 100 15 N m (74 11 lb ft).
2 4 - Before assembly, lightly lubricate the bore.
3 4 - Before assembly, apply retention compound to secure O-Ring.
D4 - - Height of the cylinder liner:
For the correct method of determining the height of the cylinder liner, refer to Testing And Adjusting, "Cylinder Liner Projection".
D5 - - Bore in the block for the camshaft bearings 98.000 0.020 mm (3.8583 0.0008 inch).
D6 - - The oil holes in the camshaft bearings must be positioned from horizontal at the angle of 20 5 degrees.
All centerlines through the oil holes in the camshaft bearings (D6) and the camshaft bearing joints (4) must be in the position that is shown for each side of the cylinder block.
D7 - - New dimension from centerline of crankshaft bearing bore to the top of the block 586.00 mm (23.071 inch).
D8 - - New dimension from centerline of crankshaft bearing bore to bottom of block (pan rails) 230 mm (9.1 inch).
D9 - - Bore in the block for the main bearings:
Standard, original new size 169.742 0.020 mm (6.6827 0.0008 inch) 0.63 mm (0.025 inch) larger than original size 170.372 0.020 mm (6.7075 0.0008 inch).
D10 - - Dimension for crankshaft main bearing cap:
Width of crankshaft main bearing cap 340.030 0.015 mm (13.3870 0.0006 inch).
Width of cylinder block for crankshaft main bearing cap 339.985 0.015 mm (13.3852 0.0006 inch).
Tight press fit between the sides of the crankshaft main bearing cap and the cylinder block 0.075 mm (0.0030 inch).
Loose press fit between the sides of the crankshaft main bearing cap and the cylinder block 0.015 mm (0.0006 inch).
5 9 - Use the following procedure to tighten the crankshaft main bearing cap bolts:
1. Install main bearing caps with the part number and "FRONT" toward the front of the block. Each cap has a number. Each cap must be installed in the same position as the correct number on the side of the cylinder block pan rail.
2. Before assembly, apply clean engine oil on the threads of the bolts.
3. Tighten bolt (1) through bolt (4) in the numerical sequence that is shown in Illustration 1 to a torque of 190 14 N m (140 10 lb ft).
4. Tighten bolt (1) through bolt (4) again in the numerical sequence to a rotation of 180 5 degrees.
D11 - - Extension of the dowel from the rear face of the cylinder block 6.0 0.5 mm (0.24 0.02 inch).
6 4 - Before assembly, lubricate the bore lightly with the lubricant that is being sealed.
D12 - - Extension of the dowel from the rear face of the cylinder block 19.0 0.5 mm (0.75 0.02 inch).
D13 - - Extension of the dowel from the front face of the cylinder block 40.0 0.5 mm (1.57 0.02 inch).