Alpha gen 2 and mercruiser 470 compatability

I have an older (87?) Aquasport 222 express with a 2004 mercruiser 5 liter carburated v8 and matching 2004 alpha gen2 drive. I love the gen2 with the v8 but it's just too heavy for this boat, at least when directly attached to the outdrive and situated near the transom. I'd like to replace the V8 with a a lighter inline engine, saving at least 200 lbs. The current setup causes the cockpit drains to be too low and reverse flow.

I'm wondering what is the best engine for a downgrade. I can loose some horsepower, thats ok. I'm wondering if a 470 engine can fit my late model alpha gen2 drive and if it would be a good choice?

Re: Alpha gen 2 and mercruiser 470 compatability

and if it would be a good choice?

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Nope,... The 470 is mercruiser's redheaded bastard stepchild that they Abandoned over 10, maybe 15 Years ago...
Many parts for 'em can't be bought at any price, anywhere,.. especially from Mercruiser...
Your Only choices for Lighter motors are the 4.3l, at about 100lbs less, or the 3.0l at about 150lbs or so lighter...

If this boat has ever floated higher in the water,...
I'd bet the floatation foam is getting Waterlogged, causing that sinking feeling...

Re: Alpha gen 2 and mercruiser 470 compatability

while i ain't the pro here, it seems to me that you have a great setup now.
i find it hard to believe that a 22' express cruiser won't tolerate the weight of a V8. assuming your not overloading it. for that matter that's likely what belongs in it if it's gonna offer any performance at all. i think i'd be finding out what the weight of your rig is supposed to be then be weighing it. i'm thinking waterlogged foam, water intrusion under the sole....
sorry don't know the answer to the question but i think there's some underlying problem here. less hp is generally not a great idea imho...

Re: Alpha gen 2 and mercruiser 470 compatability

A switch to a 470 would be a HUGE downgrade in power and an even bigger maintenance NIGHTMARE. Horrible idea. Maybe the worst idea I have ever heard.

bond-o is hitting the nail directly on the head. If that boat ever rode higher in the back, and now it sits too low, you've either got water laying in the hull, or you are severly over/improperly loading the boat. ziggy is also right on, a 22' boat should handle a V8 in the back ALL DAY LONG with NO problems.

You have some other issue.

Re: Alpha gen 2 and mercruiser 470 compatability

Maybe the worst idea I have ever heard.

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um.....no......I would say that switching to a 460 King Cobra would take the prize!! The 3.7L swap could be a close second though......


I would suggest staying with the V-8 + GenII.

Do you know what engines it came with when new?

Re: Alpha gen 2 and mercruiser 470 compatability

Ok, I get the message - Bad Idea. The mercruiser is the smoothest engine I have ever seen, and other than a bad oil pressure switch has had no problems. It's really quiet and uses surprisingly little gas. Ok - I'll keep it. I think the original equipment was similar. I want to hang a 200 lb kicker on the transom also, hence the weight issue. I've thought about using a jackshaft and moving the engine forward 2 feet tocompensate, but that's a lot of work. I'll check for waterlogged flotation below the deck. I'll have to cut a port to check.

My original concern developed because I noticed that even in calm seas out of oregon inlet that while slow trolling a following 2 ft sea would rise to within 10 inches of the top of the transom. I could easily see a bigger wave coming over the stern if it was steep. Maybe this is just paranoia, enhanced by the fact that I believe that if swamped the boat will sink. It has no scuppers to let the water out, even if the deck were to be self bailing.

Any thoughts regarding a jackshaft?

Re: Alpha gen 2 and mercruiser 470 compatability

Bad Idea. The mercruiser is the smoothest engine I have ever seen, and other than a bad oil pressure switch has had no problems

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First of all, the 470 is the ONLY Mercruiser engine that was made, the V8, the V6 and the 3.0L are all GM (Chevy) engines.
The 3.7 (aka 470) was an aluminum block (open deck design) designed by Mercruiser and used an iron Ford 460 head.
Bad idea in the long run. An overheat would take out the head gaskets due to design. Then we get into the problem areas..................

Leave your boat alone, following seas climb into boats at times. Without seeing or knowing your boats style, or size of waves you are dealing with, I would be you are seeing a normal situation.