Mercruiser 165 Inline 6 Engine swap

[anthonylind]

I am wondering what engines I could swap for my Mercrusier Inline 6 with the "least" amount of work? I realize there probably is not going to be a direct swap unless I find the same inline 6 close to the year I had. Pulled the engine and found out my block was cracked in the water jacket. Had a family member who is a welder attempt to weld it and it cracked more. Serial Number on my cracked engine is 4215071. Any advice on whether I should just get a whole new engine or try to find a block and just keep mine would be helpful. My boat is a 1974 Invader (at least thats what the title says). I should have plenty of room in the engine bay and I would have no problem modifying that to fit an engine if I could easily connect new engine with same mounts and possibly outdrive.

 

[anthonylind]

I found a local engine on craigslist that is a 1979 Mercrusier 470 that is the engine and complete outdrive for $2000. Any idea if this is an option. Closest boat mechanic that I trust is almost 2 hours away.

 

[Scott Danforth]

RUN, dont walk from the 470. it is unique, and has a unique drive.

your best bet for minimum work is another 4.1 liter / 250 cubic inch. I suggest for your 165 is to get a block and cylinder head from a salvage yard (and 1968-1978 GM 250 cubic inch with separate head/intake). pull one from a truck if you can find it. A mild rebuild will cost you about $1500 at your local machine shop (new pistons & rings, regrind crank, condition the rods, valve job, etc.).

or take a running 250 cubic inch motor from the same truck, install brass core plugs and a marine head gasket, then move your marine accessories and intake/exhaust over.

 

[Scott Danforth]

BTW, Welcome aboard

 

[Bondo]

Ayuh,.... Welcome Aboard,.... As Scott says, ya Don't want a 470,.... No how, No way,.....

Another 250 Chevy will be the easiest swap,....
A 4.3l Could be swapped in, with some extra parts, pieces, 'n new forward motor mounts,.....

 

[Alumarine]

If you get one from a vehicle make sure it has the front starboard motor mount attachment ear.
It's still possible to fab up an attachment point though if it doesn't have it.

 

[anthonylind]

So as far as I can tell my block is the only thing bad on my engine. Theoretically if I can find a 250 block I can use the camshaft, etc. from my old engine? Also will need a new exhaust manifold as it has been "repaired" at least 2 times as far as I can tell.

 

[Bondo]

Theoretically if I can find a 250 block I can use the camshaft, etc. from my old engine?

Ayuh,.... You'd do better findin' a runnin' motor, strippin' it to a Long Block, 'n boltin' yer accessories onto it,....

A bare block would need machine work, you'd be rebuildin' it,...

 

[anthonylind]

I have located one, possibly 2 Mercruiser 160 inline six engines that I have no clue on the condition of. Is that block the same as the 165? The one 160 I looked at is questionable and would be a gamble because it wasn't properly covered but he offered me the whole engine and outdrive for what I thought was a somewhat reasonable price. I figured I could make back most of the money selling the parts if it didn't work out.

 

[Scott Danforth]

the 160 is an older version. I believe it was 230 cubic inches, however I am not sure. I would personally go the route I mentioned prior, or Bondo Mentioned. Plenty of low mileage (under 60,000) engines on http://car-part.com/cgi-bin/search.cgi for about $450 (look for 1980 chevrolet 10 series)

However ebay has a mercruiser 165 for $100 http://www.ebay.com/itm/mercruiser-Inline-6-Cylinder165-Hp-Gasoline-Engine-250-Chevy-/351681851048, however its a gamble where the running motors are less of a gamble.

 

[Fishermark]

With the truck engine, you do not need to worry about changing any of the internals - not even the camshaft. Main concern is the front mounting tab as mentioned.

Any other alternative, including the 4.3 liter V6 is going to require a lot of work.

Take a look at the picture - the two homes on the left side of the engine block... not all blocks have that tab. It is a lot easier if you can find one that does.

 

[anthonylind]

If I made the switch to the 4.3 would I also have to change the outdrive as well? And thank you guys for all the advice. Super helpful!

 

[Bondo]

If I made the switch to the 4.3 would I also have to change the outdrive as well?

Nope,.... The front motor mounts, 'n the exhaust down pipe to a Y-pipe,...

The drive don't care, might need a different prop,...

 

[anthonylind]

So I am hoping this is one of my final posts on this thread. I found another inline 6 that is just a few years newer than mine. Problem is its 4 1/2 hours away and I don't know for sure if it runs good. The guy started his own boats part business is my guess and said that he bought out a couple local guy when they went out of business. The engine is from one of those previous guys and is marked good. Said he would honor it as good for whatever that is worth.

What I am wondering is if there is a way to at least try to start the engine before I fork over the money? Its sitting on a pallet in his shop. Can I bring a battery and somehow hot wire it to at least see if it turns over? From the picture he sent it is a complete engine with starter and all electronics it looks like (and manifold). Or am I stuck turning it over by hand to make sure its not stuck and just examining it with the naked eye as best I can?

I am praying this is going to be the ticket to getting me up and running again.

 

[Bt Doctur]

Now you could look for the 292 cu in inline 6 200Hp bore it .030, add a little hotter cam a much bigger prop or a gear change and make close to 260Hp
direct bolt in, except for the exaust rubber. you need wet exaust hose because the motor is 2 inches taller

 

[anthonylind]

Will it ever end..... I'm real close to giving up on this boat. Used engine I found was cracked in the exact same spot as my original engine was.

So here is my last straw I think. Found a guy who has a OMC straight six that he is willing to sell and its actually close. Do you guys know what that conversion would look like? It's a couple years older (73 vs. 75 on my boat). Any help would be extremely grateful.

If this doesn't work I'm probably just going to get a different boat.

 

[Bondo]

So here is my last straw I think. Found a guy who has a OMC straight six that he is willing to sell and its actually close. Do you guys know what that conversion would look like? It's a couple years older (73 vs. 75 on my boat). Any help would be extremely grateful.

Ayuh,.... Ya can't just drop in the OMC motor, as nothin' will fit properly,.....

Ya gotta strip the OMC motor down to the Long Block configruation, then put all the Merc accessories on it, Then drop it in,.....

 

[Fishermark]

Like Bond-o says you will need to put the Mercruiser stuff on... but yes, it is very do-able, and not difficult.

 

[anthonylind]

By accessories what are you talking about specifically? Head, distributor, fuel pump, exhaust manifold, wiring harness, thermostat? From the pictures he sent I was hoping I would be able to take the flywheel housing, engine coupler & maybe the flywheel off my old engine and put them on the omc and then be able to stick it in.

 

[Alumarine]

Take a look at the pictures he sent.
Basically the stuff that looks different than your current motor will have to be swapped.
It's very doable. Head, should be fine. Thermostat will probably not be a deal killer.