Not true with a 454 block. 454's have water jackets between the cylinders which limits your bore to .060 or so. Some earlier 454 blocks I've seen up to .100 plus over but I'd never take it that far. Some will take a Siamese 502 to the max however not recommended by most. 4.500 is not real uncommon. Much over that is up to individual. Some will take up to 4.560/4.600. So in a nutshell not advised to go over 4.500 bore on 502. Anything over that your looking at aftermarket block. Dart, Merlin, etc.

Plus if you get over 4.250 stroke your looking for potential long or short term catastrophe. Again some have clearanced for a 4.500 stroke/ 6.385 rod but not real common for daily drivers. Yes it can be done. Is it recommended? No.

Like we pretty much confirmed until you could actually identify what block and internals it's hard telling what it is.

If I wanted that boat I'd price it intending on new power and rigging and collect what I could for that heap sitting in there. The rigging is aweful and no respectable loving boat owner would let that happen. But let the fun continue...;)

That is a stock 7.4 MPI mercruiser with stock Oval port heads and Intake with the plastic removed. Its not a mag. The mag has the Rec port intake with the Air intake turned to the side. Turned to the starboard I think.

Chris

mefi 1 ecm = old

what ?

Wai a minute before you answer that. I have to shoot up with something or lick some paper tabs first before I hear the answer,

Hi Chris, thanks for your feedback. I'm a newbie, so I just assumed all Mercruiser big blocks where Magnums? I got that from this page:
https://www.perfprotech.com/blog/boa...marine-engines

When they get to the section discussing the L29, the subtitle is "Mercruiser 7.4L Magnum MPI (L29) Models"...and below they show a photo of the mystery engine that this thread is about.

I've read some other forums and there seems to be lots of confusion as to what is a Magnum, as apparently, Mercruiser would also put the "Magnum" badge on some 330HP motors, not just the 385HP.

So confusing....however, I will say that the engine covers that are missing from this L29 do NOT say "magnum" on it. So going by that, you're correct, it's not a Magnum then?

I'm a newbie, so I'm not sure what you mean by "rigging". I'm assuming just the cabling and wires? I guess that's considered messy from the photo?

I have no idea what this means. :(

What ever you want to cal it, its a stock 330 hp mpi non mag motor. That FI system on there is great for 330-350 hp or so but it would not feed a 572. I think merc took stock 454 FI truck motors and added a few parts and plastic to make the 7.4 mpi. They might have changed the cam a little. Great motors in their day.

Chris

The wiring is quite a rats nest. Anyone going through the trouble to put a 572 in there would've cleaned that up.

1rst generation of MErcuryFuelInjection.

Black bilge, plastic battery bucket??????????? Run Forest run. This looks like a backyard throw together job for a flip. I agree with the typo idea where he meant 502 instead of 572 just to be nice. Just to call it like I see it, clueless is selling a pieced together boat for a money maker and there are more problems than whatever the purchase price is to be spent again.
Good luck.

Expedite some goodies over this way PLEASE. I'm not sure I even understand anything anymore so I might as well be out to lunch all together catchin bugs. Ha

The guy doesn't know what kind of boat he bought but tells you he knows the engine is 572????

Ok, I have an update.
I went to see the boat (2 hour drive through the countryside...lots of cows).
It's a complete basketcase in my opinion (and everyone else's so far on this forum, without even having seen the boat...hahah).

I won't go into too many details of the boat. Let's just call it the "30' Offshore Boat of Doom".
The hull and stringers looked solid. No blisters anywhere underneath, but I'm no expert. I didn't see any obvious signs of damage.
The interior is a disaster. Ripped vinyl. Looks like the two captains chairs belonged in a disco.
The wiring is a disaster. I suspect nothing actually works, and I would say it is definitely not seaworthy as is, although the seller claims he's had it on the water a month ago.
The engine compartment is filthy and oily.
We've had some really heavy rains here the last couple of weeks and the boat has been outside with no cover, so everything is soaked with about 6 inches of water in various locations around the inside of the hull.

The owner was actually a nice older guy. Didn't look like a salesman at all. LOL. He let me stay on his lot for hours checking out his boats. He seemed as curious about this particular boat as I was. LOL.

The motor actually looked decent in person. Pretty clean. He started it up and it made almost no exhaust smoke, sounded good, started easy. Actually, it's believable to me that the motor may have been rebuilt in the last couple of years.

I did find the Mercruiser tag on the block, near the starter and the number is 0L02nnnn (I'm ommiting the last 4 digits as there's no point looking at them anyways).
This page says (great resource BTW):
https://www.perfprotech.com/mercury-...gines#hp-table

So it's either a:
"7.4L BRAVO (MPI)(GEN. VI) GM 454 V-8 1998-2000" with a serial number range of 0L010003 to 0M024330
or
"454 MAG MPI BRAVO (GEN VI) GM 454 V-8 1998" with a serial number range of 0L010029 to 0L058399

Which is kinda odd to have two descriptions, albeit very similar, with overlapping serial number ranges.

Also the outdrive is definitely a Bravo One, but it is really beat up. I could "lift" the entire drive by the propeller a good 6 inches. The trim cylinders weren't moving, but where they bolt on to the rear of the drive had a huge amount of play. Ugh.

At this point, the boat is worth the price of the triple axle trailer it was on and the 20 year old motor. So what's that, like $3K?
Here's the problem. I'm a sucker for basketcase projects. This boat is calling me. She haunts my dreams....

It's the 7.4L Bravo. The Magnum has totally different intake and fuel injection system.

You still want this boat ?

Have you ever stood in a boxing ring with Mike Tyson ?

What kind of boat? How much are they asking? How much are you willing to put in it? Are you retired without any other obligations and able to dedicate a full time year to this project? If you're married are you trying to get divorced?

Even if he puts the trailer on your hitch and hooks the safety chains don't do it. Pull the pin on your receiver and get out of there.

We don't know the year. LOL. I suspect late 1970s or early 1980s. It's a 30 footer.
He's asking a ridiculous $12K for it....to me it's worth about $3-4K as is, with the trailer.
I'm willing to strip it down, paint it, and put a new interior in. I would do all the work myself. I've done fiberglass and auto body before, so the skillset will help.
Like I said, I like projects. LOL.

Looking forward to the build thread. We love that stuff. :)

Most likely it needs stringers and a transom and fuel tank . Better budget another 3 grand and that is if you are doing all the labor on the replacement .

That's the computer plugged into the wiring harness on top of the engine

I enjoy projects as well, but I would personally search for something with more up to date hardware.

You Re insane.

If you want to throw your money away, I will PM you with my Account number and you can wire it to my bank.

I can blow through it in a hour or 2.

If you are ready for a real project, I can sell you a nice 38' formula on a trailer, and tommy "the spider" monza can help you put it back together again (like humpity dumpitee)