3litre to 470 conversion

Has anyone successfully done a conversion from the ultra reliable but underpowered 181 cid 3 litre to the older but far more powerful 470 ? Will the 470 bolt right up to an alpha1 gen 2 ?

if you can bolt it up to the rear motor mount for the GEN II transom housing, the answer is yes

Stronger, yes!
But don't lose sight of all the issues with the short lived Mercruiser 3.7L engines!


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Have you researched the known issues of the 470 / 3.7 style motors ??----Talk to your local shops to see what they think of this swap.

Ayuh,.... Why O Why would ya swap in a motor ya can't buy parts for,..??..??..??

The 470 is Merc's redheaded bastard step-child, they've totally forgotten about,.....

I've not owned one, nor would I have.
During my years of having a small marine repair biz, I have worked on them.
I have also had many conversations with other mechanics, and with a very good friend who is in the used Marine Parts Biz, regarding this particular engine.

Great concept, great torque, great power......., and all from 4 large cylinders!
The faulty charging system can be replaced and corrected.
The old school Kettering Ignition system can be updated.
The FWD end of the camshaft drives the Circulating Pump impeller, of which creates the need for an odd and unusual special seal located within the front engine cover.
Front engine covers are known to warp.
These engines tend to vibrate more so at certain RPM.

Merc discontinued this engine shortly after production began. I believe that these ran from 1978 to 1982 or so.
Perhaps ask yourself why such a short life span????


Great idea, just lacking a tad bit more research and design work.


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One more opinion


1. They were manufactured from 1985-1989

2. They had at least two design changes to the manifold systems (aluminum and cast iron mixes) and many to the charging systems mainly the rectifier/regulator assembly.
2a. The design was that similar to an outboard using a separate stator and a water cooled rectifier system

3. Mercury was forced to warranty them into the mid 1990's due to the internal failures on properly maintained boats. Mainly number 1 and number 4 cylinder (piston and or piston rod failures.)

I have worked on many, rebuilt a few.........not pretty but pretty expensive!

They are extremely sensitive to overheat issues (lack of incoming cooling water [refer to 2a]) and also thin walled manifold castings eroding causing raw water to enter exhaust and thus entering the engine and causing catastrophic damage.

If they run they run great but one trouble begins it is only a matter of time before it fails or you run out of money and patients.
And as said parts are becoming more scarce!

If you have found a good one, simply convert the charging system to a one wire alternator and the ignition to a Pertonix electronic conversion if the original Delco distributor is there and good luck!

Apparently I was incorrect. The year range is greater than I had thought it was.
It looks as though this 224 cu in/3.7L engine design ran from 1976 to 1989.

• 470 (2 BBL.) MERCURY 224 I/L4 1976-1979
• 470 (2 BBL.) MERCURY 224 I/L4 1980-1982
• 470 (2 BBL.) MERCURY 224 I/L4 1983-1984
• 485 (2 BBL.) MERCURY 224 I/L4 1980-1982
• 170 (2 BBL.) MERCURY 224 I/L4 1985-1986
• 165 (2 BBL.) MERCURY 224 I/L4 1987
• 3.7L (2 BBL.) MERCURY 224 I/L4 1988-1989
• 488 (4 BBL.) MERCURY 224 I/L4 1983-1984
• 190 (4 BBL.) MERCURY 224 I/L4 1985-1986
• 180 (4 BBL.) MERCURY 224 I/L4 1987
• 3.7LX (4 BBL.) MERCURY 224 I/L4 1988-1989
• 470 MIE MERCURY 224 I/L4 1980-1981 (inboard)

My mistake I meant 1975 which should have been 1976-1989