470 (165 hp)Mercruiser in 20' Seafari

[Fr. Frank]

You'll need to use the whole thing, motor, drive, and transom assembly. The older transom assemblies won't match newer drives and vice-versa.

The 470 is 170 hp, not 165. (470=4cyl+170 hp) There was also a 485 sterndrive unit, which was 185 hp; and 488/188 hp and 490/190 hp versions The only difference was the carburetor and intake manifold. the 470 used a 2 bbl. carb, the 485/488/490 used a 4 bbl. The 490 was only made in 1983.

It is NOT half of a Ford big-block, contrary to rumors, although most of the reciprocating parts interchange. Designed by Ford and cast by Ford for Mercruiser, the 470 is a 3.7 liter aluminum block/iron sleeved motor, with cast iron cylinder head. The cylinder head IS straight from the Ford 460 ci big block.

The raw-water cooled versions of this motor had corrosion issues with the block to head interface. The fresh-water cooled motors were great motors.

In 1984, we replaced twin raw-water cooled 470 Mercruisers out of a 26' SeaRay Sundancer with new twin fresh-water cooled long blocks. We put intakes off of a 485 Mercruiser on them, and changed the carbs to 600 cfm ThermoQuad 4 bbls with vacuum secondaries. Everything except timing else we left alone. We were able to get 215 hp out of each of those motors measured at the propeller shaft. You used to be able to get a longer-duration cam for them, too, but I doubt anyone makes them anymore. They were supposedly good for 225 hp with that cam.

Good motor when properly set up and properly maintained. The fresh-water cooled version weighs just 65 lbs more than the 3.0 130/140 hp motors.