16257 Mercury SCREW, FLOAT

To prevent damage to the inlet & exhaust valves, an adjustment must be made to the inlet & exhaust valve clearance setting. Loosen the nuts on each rocker arm and move the adjustment screw on each rocker arm away from the bridge as far as possible.
1. Put engine in position on Tool (A) and turn the engine over on its side. Make sure the blocks that are used as support for the top of the engine are against the cylinder head only and not against the exhaust manifold or valve cover bases. 2. Loosen the nuts that hold each connecting rod bearing caps (1) in position. Turn the crankshaft if necessary to loosen all the nuts. Make sure the nuts are still tight enough to hold the bearing caps in place when the crankshaft is turned. 3. Turn the crankshaft so that the "V" mark on the crankshaft gear is in alignment with "V" mark (3) on the idler gear.4. Remove the bearing caps that hold the connecting rods in position against the crankshaft. 5. Remove bearings (4) from each bearing cap. Make sure that each bearing is kept with the bearing cap it is removed from for correct installation purposes. 6. Remove crankshaft main bearing caps No.2 through No. 6 for the 3412 Engine and bearing caps No.2 through No.4 for the 3408 Engine.7. Push the pistons as far away as possible from the crankshaft. 8. Remove bearing (6) from each crankshaft main bearing cap. Make sure that each bearing is kept with the crankshaft main bearing cap it is removed from for correct installation purposes. 9. Remove two thrust-plates (7) from the center main bearings. 10. Fasten Tool (B) and a hoist to the crankshaft as shown.11. Remove the No. 1 and No. 7 crankshaft main bearing caps for the 3412 Engine. Remove the crankshaft main bearing caps No.1 and No.5 for the 3408 Engine.12. Use Tool (B) and a hoist to remove crankshaft (8) from the cylinder block. The weight of the crankshaft for a 3412 Engine is approximately 181 kg (400 lb). The weight of the crankshaft for the 3408 Engine is approximately 143 kg (315 lb). 13. Use Tool (C) to remove gear (9) from the crankshaft. Use Tool (D) to remove the dowel that is under the gear if a replacement is necessary. 14. Use Tool (E) to remove pin (10) from the crankshaft if a replacement is necessary. 15. Put identification on bearings (11) and (12) as to their location on the cylinder block or connecting rod. Remove bearings (11) and (12).Install Crankshaft
Do not put oil