engine swap, 4.3 to 5.0?

[tazzerblue5]

Will this bolt right in a 1996 Maxum? I would be replacing the outdrive also. The 4.3 block cracked. Just curious if the hull is made for a direct fit for the engine mounts. Thanks.

 

[greno]

The mounts should work if you have room for the longer block and accessories out front.

 

[Maclin]

What model is the Maxum? If you can find out if that model had a 5.0/5.7 as an option, there is your answer regarding room for engine mounts.

 

[Scott06]

You need about 4” in front of the engine of space. As outlined above the front motor mounts will be 4” farther forward. If your boat was offered with a 5.0 most likely the room will be there and stringer mounts will be be able to accommodate both 4.3 and 5.0 engines

I did this on a 20 ft sea ray 200 was able to swap all accessories wiring harness flywheel cover starter etc over to new engine. You will need new exhaust elbows that go between the y pipe and the risers. I don’t think your 4.3 is late enough to have metric starter flywheel cover and side motor mounts metric like mine did but worth checking. Not a big deal if they are metric was not an issue getting correct bolts

on the drive I kept my 1.84 drive just went from a 19” to 21” prop works fine

only comment I would make depending on your boat size a 5.7 costs the same to drop in as a 5.0 (unless you already own the 5.0). I’m very happy with my swap but I had concerns on putting in a 5.7 as too much, but there are times when fully loaded I wish I had a few more ponies.

 

[Rick Stephens]

Not enough difference between output horsies to justify the cost of a 5.0L as an upgrade to the 4.3L. And from a cost standpoint, the 5.7L will cost exactly the same.

However, you need to post model boat before you get an informed answer.

 

[tazzerblue5]

Maxum is a 190, 19' model.

 

[Scott Danforth]

a replacement 4.3 would be the least expensive to drop in.

5.7 will drop in, however as you already mentioned, will require a different outdrive.

transom key-hole is the same, however the mounts on the side are a few inches forward and the front of the motor is 4" forward

 

[greno]

If you don't yet have the V8 go for the 5.7L. Vortec heads preferably. Even in a 19' boat the 5.0L is way underpowered.

 

[bman440440]

If you don't yet have the V8 go for the 5.7L. Vortec heads preferably. Even in a 19' boat the 5.0L is way underpowered.

not true... my 4.3 is a screamer(in my maxum)... with 47 gallons of fuel, 3 fat guy's, 32 bait tank, 80 lbs of ice in a kill bag and all our gear I have PLENTY of power... going out of the bay I did open it up just to see and I could reach 49 MPH... with a light loat 55+... When I take the family/friends out tubing with 8 people (and the same 21" prop) I have ZERO problems getting on plane fast or pulling the tube with 3 people on it of the original 8... Have I ever thought that I needed more power... NO... have I ever wanted more power... NO... and I love going fast!

 

[greno]

49 MPH is about what they do. Some of us want more. Mid 60's. And cruise at about 45.

 

[Rick Stephens]

Maxum is a 190, 19' model.

So yeah, a 5.7L would be a better upgrade than the 5.0L. Without a lot of trouble or near the cost you can fix up a 4.3L to be purty near the same HP as a stock 5.0L. That said, the issue I have with swapping to any V8 is the cost. Not only do you need to build a motor, but you need new exhaust, probably need to fiberglass in modified motor mounts - maybe not, as I would bet that a 19' Maxxum had both 5.0 and 5.7L options, so the mounts might already be long enough. And you will need to swap out the 1.84:1 outdrive for a 1.5 or 1.64:1 drive. The motor is the easy part.

Still in all, the easy way, is to find a water damaged donor boat with a V8 and pull the power package. That's how I went from a 3.0L to a 4.3. I pulled literally everything from a newer boat and replaced everything in mine with the complete powertrain. Definitely doable. If you have lots of dough to spend, that might not be an issue.

Rick

 

[achris]

If you don't yet have the V8 go for the 5.7L. Vortec heads preferably. Even in a 19' boat the 5.0L is way underpowered.

I agree with the bman440440 . My 20 footer is heavy for its class, and the 4.3, even the pre-vortec, is a nice match. That engine ended up in a 23 footer and it is no slouch, hitting 36 knots. The MPI in my boat pushes it up to 43 knots, and where I operate, I'm one of the fastest boats around. Not that weather conditions allow that sort of speed very often.

I also agree with other comments saying if you go the V8 route, get a vortec 5.7. No weight penalty, but about 40hp over the 5 litre. But given that the boat is already set up for the 4.3, and to replace a long motor is quite simple, and the the 4.3 is lighter, I'd stay with that.

JMHO

Chris....

 

[greno]

The Maxum 19's always had V8 options so motor mounts should be a non-issue. The outdrive needs to be either 1.47 or 1.50. You can either install a 1.47 upper gear set, find a good used/new 1.47 upper, or find a good used/new 1.47 complete outdrive. The gear set you can find for about $178. I just did one. eBay has lots of options for swapping the drive/upper. Other than that the engine swap should be pretty straightforward.

 

[achris]

The Maxum 19's always had V8 options so motor mounts should be a non-issue. The outdrive needs to be either 1.47 or 1.50. You can either install a 1.47 upper gear set, find a good used/new 1.47 upper, or find a good used/new 1.47 complete outdrive. The gear set you can find for about $178. I just did one. eBay has lots of options for swapping the drive/upper. Other than that the engine swap should be pretty straightforward.

The purchase cost of the gear set might only be $178, but the purchase price of the special tools to set them up is the best part of a grand. And you can't just pull the old gears out and put the new ones in, they must be set up with backlash and preload, or the life of that gear case will be measured in days, not years.

Chris....

 

[greno]

Yes, I have all the special tools to do that job. And you can find those tools for far less than a grand on eBay. That's how I got mine. Not knowing the skill level of this guy I put it out there as an option. Probably easiest option is to just find a good upper on eBay and sell what he's got back on eBay.

 

[tazzerblue5]

Well, I'm watching CL for donor boats and a 5.0 came across for a reasonable price. 1200.00 boat and all. It will be a few years older but I'm looking at 2k for a long block 4.3 I'l attach the photo's of the 4.3 I just tore it down today. I bought it this way. Such a waist. I don't plan on getting it up and running this season anymore. I farm and have a lot of other equipment to get ready.. Thanks for the reply's..

 

[Scott Danforth]

you can get running 4.3's from trucks for about $300

re-mans from your local builder about $1500

 

[greno]

Yeah, from the pictures that block is toast.
Here's a good Mercruiser 4.3L block on eBay for $300+ship.

 

[Scott Danforth]

block from a pull-a-part is $50
complete motor is $275

https://www.lkqpickyourpart.com/locations/LKQ_Pick_Your_Part_-_Tampa-180/prices/

 

[greno]

If you go the reman Mercruiser marine block route, a machine shop can bore and hone the cylinders for about $90. If they bore it .020 over then just get a new set of .020 over pistons and rings ($125-250, Summit or Jegs) and you already got everything else from your old engine. That way you know everything is going to fit.