NEED HELP QUICK PLS: Replacement Engine choices for 350 MPI

[Hai Nhi]

Hope everyone is well and pumped up for the boating season.

I'm looking for the replacement for my Mercruiser 350 Mag MPI (1999). I found a 2004 monsoon 335 engine pulled out from a house boat with 300 hours. This is a GM 350 engine.

The question is: since it's setup as an inboard engine, can I swap with mine?

My stern is a bravo I. What additional part do I need if it's not a direct swap?

It's about $3000. Let's say I can afford a new 6.2 300HP @$11,000, which one is a better buy?

Thanks

Nhi

 

[kenny nunez]

Is it a standard rotation as with a stern drive left, or a right rotation that plenty single marine engine straight inboard have?

 

[Rick Stephens]

Have to know why you need to replace a motor before answering the question. Usually the best solution with a SBC is to replace the block and internals and reuse all the external odds and ends.

 

[Hai Nhi]

Is it a standard rotation as with a stern drive left, or a right rotation that plenty single marine engine straight inboard have?

Thanks for noting Kenny.

Sorry I omitted one detail: it’s a dual engines setup. These are also taken from the same boat so I assume they’re already counter each other.

 

[Bondo]

Thanks for noting Kenny.

Sorry I omitted one detail: it’s a dual engines setup. These are also taken from the same boat so I assume they’re already counter each other.

Ayuh,.... For a sterndrive application, you need a standard, lefthanded motor,......

If the accessories on yer current motor are good, just buy a long block, like Rick says,.....

 

[nola mike]

You can get a reman 5.7 for about $3k, and a 6.2L for $4500. As the others alluded to, nothing special about your setup--it's a standard GM block. If I wasn't going to do anything to it, I'd sooner get a used truck engine than a (much more) expensive used boat engine (in fact, I did that).

 

[Hai Nhi]

Thanks for all the quick responds.

here are some more pointers:
- I brought my boats to 2 shops for estimate and they said I should replace instead of fixing.
- it was a salt water boat. Got neglected 5-6 years ago. I got it and left it outside uncovered for 3 years or so. I have to take a look at it again today and snap some photos for you to see the outside condition. Back then, one engine got locked. The other one turned.
- this will be a cruise around boat. Not to be racing or anything like that.

some other questions are:
- in what conditions of the other parts to be worth saving ? I’m just afraid that when buying the base engines home, then find out the hard way that the rest also need replacement.
- marine Vs truck engine: I thought there are a lot of differences?

thanks.
Nhi

 

[achris]

...- marine Vs truck engine: I thought there are a lot of differences?

Head gaskets, core plugs, water pump. That's it...

 

[Hai Nhi]

I see Michigan Motorz is selling quite a bit of different configurations. Is there any other places to get them from too?

For reman vs new, different is about $1000 (for 5.7). Is it worth the saving?

sorry for all the newbie questions. I’d just like to make some informed decisions.

thanks much in advance.

Nhi

 

[Rick Stephens]

A salt water boat may need any component that salt water runs through - manifolds, both exhaust and even intake, engine blocks, heads and so on. Going to take some analysis of the condition of everything to answer your question.

 

[QBhoy]

If twin engine and bravo one. Surely the rotation would be critical. The starboard will be standard LH and the port will be RH, mostly.

 

[achris]

If twin engine and bravo one. Surely the rotation would be critical. The starboard will be standard LH and the port will be RH, mostly.

NO, no, no!

ALL stern drive engines (that includes Bravo drives) run standard rotation, ALL. The counter rotating is done in the drive, NOT by spinning the engine the other way....

 

[QBhoy]

NO, no, no!

ALL stern drive engines (that includes Bravo drives) run standard rotation, ALL. The counter rotating is done in the drive, NOT by spinning the engine the other way....

That’s not true chris. I know it’s true on the VP. Not single prop mercruiser a though. What makes you think that ?
Certain by 100000% it’s not true on the alpha at least. Presume it’s the same on the bravo one.
If you like, I can show you at the weekend. On a twin 4.3 and alpha set up. 100% the port engine is rH

 

[achris]

That’s not true chris. I know it’s true on the VP. Not single prop mercruiser a though. What makes you think that ?
Certain by 100000% it’s not true on the alpha at least. Presume it’s the same on the bravo one.
If you like, I can show you at the weekend. On a twin 4.3 and alpha set up. 100% the port engine is rH

Can't be. The engine will be LH, the counter rotation is in the lower housing. Of that I am 10000% certain, and if I had time is give you about 10 reasons it can't be, but I'm on the way to the airport. When I'm home next week, I'll reply to this thread again explaining why there is no RH engines on Merc Stern drive.

 

[QBhoy]

Can't be. The engine will be LH, the counter rotation is in the lower housing. Of that I am 10000% certain, and if I had time is give you about 10 reasons it can't be, but I'm on the way to the airport. When I'm home next week, I'll reply to this thread again explaining why there is no RH engines on Merc Stern drive.

I may be wrong about Bravos. Perhaps they can alter the rotation in them. But I’m certain the twin 4.3 with alphas I know of, are the engine that’s reversed.I assumed all alpha set up would be like this if the prop is LH on the port side ? I remember this particular boat owner I mean, having this, I’m sure. It’s in my yard now. I’ll have a look at weekend.

 

[achris]

I really only need to show you one thing to prove that you can't put a RH engine in front of an alpha drive...



If you turn the drive shaft and gears backwards, you'll never lock this clutch, it'll just keep ratcheting over the ramps...

Chris.

 

[Scott Danforth]

That’s not true chris. I know it’s true on the VP. Not single prop mercruiser a though. What makes you think that ?
Certain by 100000% it’s not true on the alpha at least. Presume it’s the same on the bravo one.
If you like, I can show you at the weekend. On a twin 4.3 and alpha set up. 100% the port engine is rH

its actually true. every motor in front of any sterndrive is standard left-hand rotation. right hand rotation motors were used on inboard applications only, and that requirement went away over 40 years ago. dont believe me, or @achris who is a trained mercruiser tech. maybe you should call mercury marine (they get this call almost daily)

Mercury Marine - A Worldwide Leader in Marine Propulsion | Mercury Marine

Manufacturers of outboard motors and MerCruiser inboard engines, with over 4000 dealers in the United States.

www.mercurymarine.com

on your twin 4.3 alpha set up, the opposite spinning props are done by simply swapping the cables at the controls and running the one drive in reverse vs fwd

 

[Scott Danforth]

Thanks for all the quick responds.

here are some more pointers:
- I brought my boats to 2 shops for estimate and they said I should replace instead of fixing.
- it was a salt water boat. Got neglected 5-6 years ago. I got it and left it outside uncovered for 3 years or so. I have to take a look at it again today and snap some photos for you to see the outside condition. Back then, one engine got locked. The other one turned.
- this will be a cruise around boat. Not to be racing or anything like that.

some other questions are:
- in what conditions of the other parts to be worth saving ? I’m just afraid that when buying the base engines home, then find out the hard way that the rest also need replacement.
- marine Vs truck engine: I thought there are a lot of differences?

thanks.
Nhi

since the motor is a salt water motor and was neglected. consider that the only thing salvagable will be the carburetor, front accessories, ignition, and rotating electrics.

the block, heads, intake and exhaust manifolds are toast

the other will not be far behind. however you will need to pull apart and inspect.

that epoxy painted intake manifold used on the MPI's is a very pricey part.

if you are on a budget, go to any LKQ pull-a-part yard and get two 1998 or earlier 350's out of running trucks. you will pay $150 for each engine. to them you need to pull them down, swap head gaskets and core plugs, then buy a marine circulating pump. then add new exhaust manifolds and build up the rest from the parts you have. this will cost you about 2 weekends of your time and about $3000 if your existing intake manifolds are pristine, or about $5000 if you need to replace them

if you have unlimited budget, get two brand new 6.2 bob-tails with factory heat exchangers. this will cost you close to $30k

 

[achris]

...on your twin 4.3 alpha set up, the opposite spinning props are done by simply swapping the cables at the controls and running the one drive in reverse vs fwd

That'll work, for a little while. Then completely destroy the lower housing. It means the REAR ball bearing (behind reverse gear) is taking way more thrust than it was EVER designed to. Here's a picture of the 2 lower housings. Note the beefed up carrier and bearing on the rear (now 'forward') gear on the CR box.



Chris......

 

[Scott Danforth]

chris, its still a LH motor with switched cables, no mater if they changed the thrust washer in the lower or not.