89 180 Horizon w/ 4.3 OMC

[djaymasa]

I just bought our first boat to restore. Found this boat with a cracked block but everything about the boat and motor is quite immaculate. I'm very new to engine repair as it is, but I have family and my son who do well enough alone.

A mechanic ran through it 2 years ago and overhauled from what I can tell. Brand new Alternator and belts at least. The previous owner used it last year but did not get it winterized over the winter. Side note, the outboard looks fine other than the 4 fin prop.

We're looking into the simplicity of swapping to another 4.3 or 5.0. I know they came with the option for 5.0 so it should be simple enough.

We are wondering what to look for, what other things are needed, if any, and is it just best to go to 5.0? I don't want to spend too much more money on this so a 5.7 is a no go. I've scoured through Google for info over the last 48 hours, but seem to get a lot of confusion...first off, OMC vs Volvo penta vs Vortec? If that's even a thing. Any help would be lovely!

 

[Scott Danforth]

Get another 1987-1990 4.3 short block and heads.

 

[djaymasa]

Get another 1987-1990 4.3 short block and heads.

That's the original intention. With the new block, is it needed for new heads?

After some shopping, we're able to find a 5.7 merc that comes with the outboard for <$600. So now we're debating this..

 

[djaymasa]

We are looking into that for sure. Ty

As for any upgrade in motor, we came across a 5.7 with the outboard for 600 obo. I'd imagine the accessories all have to be swapped as well?

Trying to figure if it's a reasonable things to upgrade or just a money dump.

 

[dubs283]

Trying to figure if it's a reasonable things to upgrade or just a money dump.

Unless you know pretty much everything about OMC cobra sterndrives it's a money (and time) dump

If you knew enough about OMC you wouldn't be asking

 

[Bondo]

We are looking into that for sure. Ty

As for any upgrade in motor, we came across a 5.7 with the outboard for 600 obo. I'd imagine the accessories all have to be swapped as well?

Trying to figure if it's a reasonable things to upgrade or just a money dump.

Ayuh,..... Welcome Aboard,..... If it's Complete, from the pulleys to the prop,..??.....
Yes, that's a wise swap,.....

Rip out all of everything OMC, 'n bolt in Everything from the Mercruiser,....

 

[djaymasa]

I found a 4.3 vortec, looks like a 3rd gen

Will this work fine if we put the original intake on it. The seller seems to thin it will work fine as well

 

[Scott Danforth]

I found a 4.3 vortec, looks like a 3rd gen

Will this work fine if we put the original intake on it. The seller seems to thin it will work fine as well

What are you defining as 3rd gen?

 

[djaymasa]

Were not totally sure, but it's definitely not early 90s.

 

[Scott Danforth]

Vortec motor. No way your intake will bolt up.

Plus all the automotive stuff bolted on the front has to go. You also need the correct flywheel.

You also have to pull the heads, and install marine head gaskets as well as change the core plugs to brass or stainless

 

[djaymasa]

Vortec motor. No way your intake will bolt up.

Plus all the automotive stuff bolted on the front has to go. You also need the correct flywheel.

You also have to pull the heads, and install marine head gaskets as well as change the core plugs to brass or stainless

This mechanic doesn't seem to agree... I'm struggling to understand it all.

Flywheel is on both motors. So we'd be able to swap right?

 

[djaymasa]

And intake? If we got a newer intake and put it on wouldn't that work?

 

[Scott Danforth]

This mechanic doesn't seem to agree... I'm struggling to understand it all.

Flywheel is on both motors. So we'd be able to swap right?

Share this with your mechanic.https://forums.iboats.com/threads/complete-history-of-the-4-3-liter-with-casting-numbers.693935/

The motor in the pic is a 90M casting metric vortec automotive motor.

If your mechanic can get your 1988-1989 non balance shaft non vortec intake to fit. He is doing better than GM and every wrench turner I know

I suggest you find a mechanic that knows what he is doing

 

[djaymasa]

Share this with your mechanic.https://forums.iboats.com/threads/complete-history-of-the-4-3-liter-with-casting-numbers.693935/

The motor in the pic is a 90M casting metric vortec automotive motor.

If your mechanic can get your 1988-1989 non balance shaft non vortec intake to fit. He is doing better than GM and every wrench turner I know

I suggest you find a mechanic that knows what he is doing

I appreciate this link for sure. So I've moved on and let the mechanic go.

So back to my initial situation! My issue with getting a new block and heads is that seems like it's a hell of a lot more work and time than it is to get a whole newer engine? Like I said, all the accessories are new and should easily go to the newer motor, right?

I can look into the short blocks as it just seems the correct thing to do. So Merc/GM-OMC it is.

 

[Scott Danforth]

Get a pre 1992 marine long block of you want to transfer your front accessories over without much fuss

I personally would get a set of vortec heads and a good vortec intake and get 1993-1995 block.

 

[djaymasa]

Get a pre 1992 marine long block of you want to transfer your front accessories over without much fuss

I personally would get a set of vortec heads and a good vortec intake and get 1993-1995 block.

I found a block, heads and intake for 4.3 merc. Basically is the whole thing, but has rod knock.

From the information I've gathered that should be everything I need to swap, correct?

I can take all the accessories off my original as well as all the innards of the engine and put them in the merc? Does the flywheel swap as well?

If this works, anything to be worried about? The outboard, after looking into it, would need some adjusting as well?

 

[Scott Danforth]

I found a block, heads and intake for 4.3 merc. Basically is the whole thing, but has rod knock.

With a rod knock, plan on a complete rebuild. You can't just swap internal parts from your motor to one with a rod knock

What year is the block you found?

What year are the heads?

From the information I've gathered that should be everything I need to swap, correct?

I can take all the accessories off my original

You can use the accessories

as well as all the innards of the engine and put them in the merc?

Nope, this is where you must involve a machine shop. Used bores require boring to true them up
Rod knocks require line-honing and main bearing cap machining at a minimum

Your outdrive needs to come off to pull the motor. Do any drive maintenance that has been neglected

Your lowest cost is to find a good and strong running motor

 

[djaymasa]

Get a pre 1992 marine long block of you want to transfer your front accessories over without much fuss

I personally would get a set of vortec heads and a good vortec intake and get 1993-1995 block.

With the vortec heads and intake, anything to specifically look for?

I can locate a block as stated. Trying to wrap my head around vortec parts on the block itself.

 

[Scott Danforth]

With the vortec heads and intake, anything to specifically look for?

I can locate a block as stated. Trying to wrap my head around vortec parts on the block itself.

Vortec heads are 1996 and later. 4 intake bolts per head

 

[djaymasa]

Vortec heads are 1996 and later. 4 intake bolts per head

I've looked into others doing this whole vortec motor swap and am confused all over again.

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