470 (165 hp)Mercruiser in 20' Seafari

[fdheld34]

Have a chance to aquire a donor boat with great running 470 mercruiser and alpha outdrive...has external alternator conversion....
Good choice or not???
I have done numerous searches etc and have read many differing opinions regarding this motor. Some love it some hate it
Any help appreciated as it pertains to dropping in a Seafari!
Fred

[bobbert]

The biggest problem has been solved. Has external marine alternator conversion. Will work just fine in Seacraft

[Bushwacker]

Fred,

A guy I used to work with used to have a Bertram 25 with a pair of 470's in it. I think they're pretty rugged engines. It should be similar weight to the 140, but more modern design and of course more power, so those are all positives. I think it may be 1/2 of a Ford 7L V-8, so durability and parts availability should not be a problem. Mounts will be different, not sure about outdrive mount. Only other downside I can think of is it's an even bigger I-4 than the 3.0L 140, so it'll buzz a little more and maybe burn a little more gas than the 140 depending on how you run it, but you'll be able to cruise faster and carry heavier loads. Denny

[jorgeinmiami]

Botapeje had that set up before he sold it.
You can see his boat in the gallery section
Nestors a real nice guy and may be able to answer your questions
l

[bobbert]

The engine will mate up with transom assembly. The problem is an alpha od will NOT install on a pre alpha transom assembly.So you are looking at swinging over the transom assembly, or using you pre alpha drive. Also the transom key hole has to be enlarged in a few areas and re-epoxied when using the alpha transom ass'y
Good luck getting ready to do the same up grade on a 65 Bertram.

[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.

FrFrank - Once again you absolutely dazzle and amaze us!!! Wish you had been around back in the 60's when I was trying to work on a 125 Rude that blew a hole in the block.

[fdheld34]

Thanks all for the info..see what I can come up with..still pondering repower..so many deals out there at the moment. Seems that the 470 would be ok so I will keep it in mind and see what happens.
-Fred

[lost2a6]

I agree with Frank, we had a guy at my fathers Marina who had a 470 in a Chris Craft Scorpion. The engine had a lot of time on it and he wanted an excuse to get a new engine. He ran the crap out of it and it wouldn't blow up. He then ran it on the trailer without water at 3000 RPM's. It ran for approximately 30 min and it got so hot that it started to miss, RPM started falling, and then it finally quit. We thought for sure that it was done for. The next day he went to the boat and hit the key and the SOB started right up and ran fine. I think that he ended up putting some lead pellets down the carb so it would get to the combustion chamber and raise cane. The only thing that I can think of besides the charging problem is the engine would shake excessively at idle, I was told this was due to its large displacement and it only being a 4 cylinder.

[Wags23]

The fresh water cooled factory heat exchanger had some problems too they sell a replacement thats bigger, less overheating problems.I had one that said 165 hp on the valve covers.