NEED HELP QUICK PLS: Replacement Engine choices for 350 MPI

[achris]

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

I know. I'm just saying that if they switched the cable (and added a LH prop), and didn't put a CR lower box on, the (existing) box is not long for this world.

 

[nola mike]

Just so this doesn't get lost, op should seriously inspect this boat to make sure it's structurally sound before spending money on it. Neglected, then neglected again uncovered for years--op needs to thoroughly check his stringers and transom

 

[achris]

Just so this doesn't get lost, op should seriously indirect this boat to make sure it's structurally sound before spending money on it. Neglected, then neglected again uncovered for years--op needs to thoroughly check his stringers and transom

Indirect? Maybe 'inspect'?

 

[nola mike]

Indirect? Maybe 'inspect'?

Groan

 

[QBhoy]

Thanks for this guys. Every day a school day on here. Said that loads now.
I think I’ve figured out why that was in my head. The searay 270 twin 4.3 alpha I was referring too, isn’t the boat I had in my head at all. It was a larger searay 310 or 340 with twin shaft driven 5.7’s. Was owned by the same guy. My bad and thanks for the info. If I hadn’t read the above...I would have bet my earnings on the mercruiser twin outdrive set up being Rh and LH...and likely lost it all. Was certain if it in my head as well. I knew the VP was done at the outdrive. Honestly thought the merc was at the engine.

 

[Hai Nhi]

Just so this doesn't get lost, op should seriously inspect this boat to make sure it's structurally sound before spending money on it. Neglected, then neglected again uncovered for years--op needs to thoroughly check his stringers and transom

Thanks for all the posts. Even though I could only follow partial of it (because I'm still learning), it was great to see the discussions.

This boat was all good and sound. I think I've checked with the Cobalt back then. And they said for my boat year, they are all fiberglass - no wood. So no need to worry about dry-rots, etc...

 

[Hai 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

First option: $3000/$5000 For both? or each?
2nd option: I don't have the everyone-dreaming-about-unlimited-budget. LOL. But I did look at that 6.2 just for measure. Man it looks so nice. I see a couple of places selling these. Not sure where people usually get new engines from?

 

[nola mike]

First option: $3000/$5000 For both? or each?

Both
Edit: just reread the thread, you only need one engine right?

 

[Hai Nhi]

Both
Edit: just reread the thread, you only need one engine right?

I think we need to do both.

 

[Hai Nhi]

I brought the boat to a local boat mechanic. They said a replacement of both engines are recommended.

I checked around for new engines and come across a pair of new 6.2L 300HP at about $23000.
However, one is 2016, other is 2019. Both are new and under manufacturer warranty (if installed by authorized dealer). These are for sure not cheap.

so questions are:
- for new drop in, what my options for this size of the boat (1999 Cobalt 292)? I see 5.7, 6.2, 383, etc. to my understanding, 6.2 300Hp is equivalent to 5.7, 6.2L 350 Hp is equivalent to 383, correct?
- new Vs used/reman: what’s the major differences other than prices?
- where to get great pricing on engines?
- the pair I mentioned is 3 years apart (2016/2019, again - both new with warranty). Would they be okay?
- how do I know for sure the fit? Should I ask the boat mechanic, or Cobalt? Or just go measure myself?
- they need to be counter rotation for my Bravo 1, correct? Sorry but I’m still not clear after reading the earlier posts.

Thanks again.
Nhi

 

[achris]

...
- they need to be counter rotation for my Bravo 1, correct? Sorry but I’m still not clear after reading the earlier posts.

Thanks again.
Nhi

Again, ALL stern drive engines are the same (LH) rotation. If the port propeller is counter rotation, that is done in the drive, not by spinning the engine the other way!

 

[Scott Danforth]

a 383 is 6.2 liters. new 6.2 liters are 377's . both are stroked 350's wiht 3.75" stroke vs the stock 3.48", however the 383 has a bore increased by .030" which is typical of a rebuild.

the 2016 and the 2019 would be identical in build other than a build date difference.

I would have no problem dropping them in your boat, however I would build my own motors prior to buying.

 

[Hai Nhi]

a 383 is 6.2 liters. new 6.2 liters are 377's . both are stroked 350's wiht 3.75" stroke vs the stock 3.48", however the 383 has a bore increased by .030" which is typical of a rebuild.

the 2016 and the 2019 would be identical in build other than a build date difference.

I would have no problem dropping them in your boat, however I would build my own motors prior to buying.

When you said build your own, meaning rebuild?

That’s what I’d love to do. One is to save money, if that makes sense of course. Secondly, I’d learn to service it better in stead of keep relying on others for small- medium service jobs.

However, what I’m stuck at is how to assess what need to be done with my engines.
I know this forum is super helpful. But I’m not sure if pictures alone can be good enough for people to help me assessing things.

 

[achris]

The first thing you need to do is get the engines out and stripped down. Only then can you assess them and work out which way to go. If you decide the rebuild route, you find a good machine shop who will help you assess things like crank, heads and block.

 

[Scott Danforth]

you can rebuild what you have for about the same cost as building new from scratch and have a better motor than the GM built 6.2. or you can buy the GM built 6.2

a new crank is always cheaper than reconditioning your current crank
a new set of rods is always cheaper than reconditioning your current rods
new pistons and rings, bearings, etc are required with any build
a complete stroker rotating assembly is about $1400

getting your cylinder heads reconditioned if they are salvageable will be $400

new cylinder heads are $1200 a pair. https://www.gmperformancemotor.com/parts/12691728.html (just last year they were $900)

getting your block baked, line-honed, decked, bored and honed will be about $700

new block is currently $1400 https://www.gmperformancemotor.com/parts/88962516.html (just 2 years ago it was 800)

a complete cam kit with cam. lifters, rockers, springs, etc is about $1400
gaskets are about $120

new brass core plugs are about $12

new oil pump, pump drive and pickup about $100

new GM head bolts $50, new GM main bolts, about $50 (New ARP studs for heads and mains about $200)

new damper is $40

a new 377 base motor will cost you $5100

Home :: Marine Engines :: New Marine Engines :: New Marine Base Engines :: New 6.2L Vortec "Stroker" Marine Base Engine (replaces years 1996-present)

New 6 2L Stroker Vortec Marine Base Engine replaces years 1997-present This is a brand new 6 2L/377 c i Vortec Marine Base Engine right out of GM Marine This engine will replace those 6 2L marine engines used in Mercruiser Volvo Penta OMC Crusader Indmar and other applications between the years

marineengines4less.com

to that, new marine exhaust manifolds and elbows are $800
you transfer over your accessories, rotating electrics, etc.

if your intake is still good, use it, if not, you must buy another GM intake

transfer over the induction system, ignition...... add fluids and you have a motor

or buy a new bobtail for $11k each

 

[Hai Nhi]

you can rebuild what you have for about the same cost as building new from scratch and have a better motor than the GM built 6.2. or you can buy the GM built 6.2

a new crank is always cheaper than reconditioning your current crank
a new set of rods is always cheaper than reconditioning your current rods
new pistons and rings, bearings, etc are required with any build
a complete stroker rotating assembly is about $1400

getting your cylinder heads reconditioned if they are salvageable will be $400

new cylinder heads are $1200 a pair. https://www.gmperformancemotor.com/parts/12691728.html (just last year they were $900)

getting your block baked, line-honed, decked, bored and honed will be about $700

new block is currently $1400 https://www.gmperformancemotor.com/parts/88962516.html (just 2 years ago it was 800)

a complete cam kit with cam. lifters, rockers, springs, etc is about $1400
gaskets are about $120

new brass core plugs are about $12

new oil pump, pump drive and pickup about $100

new GM head bolts $50, new GM main bolts, about $50 (New ARP studs for heads and mains about $200)

new damper is $40

a new 377 base motor will cost you $5100

Home :: Marine Engines :: New Marine Engines :: New Marine Base Engines :: New 6.2L Vortec "Stroker" Marine Base Engine (replaces years 1996-present)

New 6 2L Stroker Vortec Marine Base Engine replaces years 1997-present This is a brand new 6 2L/377 c i Vortec Marine Base Engine right out of GM Marine This engine will replace those 6 2L marine engines used in Mercruiser Volvo Penta OMC Crusader Indmar and other applications between the years

marineengines4less.com

to that, new marine exhaust manifolds and elbows are $800
you transfer over your accessories, rotating electrics, etc.

if your intake is still good, use it, if not, you must buy another GM intake

transfer over the induction system, ignition...... add fluids and you have a motor

or buy a new bobtail for $11k each

Thanks for the detailed post.

In what sense building new by myself is better from buying the bobtail set up?

If building from scratch, I’d like to build a sea core equivalent setup. What components in my build should be purchased other than the fresh water cool setup for this? I heard about stainless steel exhaust manifolds?

From the example above, buying pieces is about $4000, vs buying a base engine, which is $5100. For less than $1000, I would also have an ARP set of studs. Is there anything else to it? If not, I think I would go this route.

Thanks

Nhi

 

[Scott Danforth]

Stock build is a mediocre motor with stock GM flat topped pistons and pressed pins vs propper LCQ pistons and floating pins. Difference is between 100-125 lb-feet and a fatter torque curve (about 50-100hp more) if you build it right yourself

Seacore is just a fancy name for HX cooled

Up to you if you buy or build

 

[Scott06]

Thanks for the detailed post.

In what sense building new by myself is better from buying the bobtail set up?

If building from scratch, I’d like to build a sea core equivalent setup. What components in my build should be purchased other than the fresh water cool setup for this? I heard about stainless steel exhaust manifolds?

From the example above, buying pieces is about $4000, vs buying a base engine, which is $5100. For less than $1000, I would also have an ARP set of studs. Is there anything else to it? If not, I think I would go this route.

Thanks

Nhi

If you are knowledgeable and talented enough to assemble your own engine ( seems like you may be from your comments) Scott can walk you though the right choices. If you arent knowledgeable or dont consider a project fun, buy the complete base engine. either route will work just one is more optimized...

 

[Hai Nhi]

Super cool. Thanks much for the great responds so far. I’m very excited.

I’m gonna clean up the yard to make room for the build next 2 weeks.

Once done, I’ll set up the crane to pull the engines. Right now the boat is on a trailer. I have one of those power hoist bought from Harbor freight for my other job. I’m Not sure if I should just build a crane, or buy a used one.

I have one long wooden beam (4x12) and a steel square tube I can use as a cross bar. I also need to pull my Chevy LLY engine out from my totaled truck anyway (I can also use my cherry picker for it).

Anyone has some pics of their setup to share?

After done with the setup, I will post pictures.

In the meantime, please help me with the list of things to buy and best place to get them from. I know Scott just posted some couple days ago. But I’m sure it was just a quick list from top of his head.

I don’t have an unlimited fund. But I think I can come up enough to buy the best parts for this do-it-myself project. So please suggest quality parts.

Again, is stainless steel manifold recommended?

Which parts would make my set up best proof against salt water other than getting the fresh water cooled systems? I will be running mainly in freshwater. But since I live only 10-15 minutes from marinas that lead to the San Francisco Bay, I will go out once in a while.

Last but not least, my bravo 1’s are in rough shapes that also need to be worked on/rebuilt. Should I look into converting them into B3? If so, what are my options?

thanks much.

Nhi

 

[Scott Danforth]

remember, your local engine machine shop guys probably are the best resource you have. Depending on how you want your build, you may need to go that route.

for a stock block, Summit or GM direct

for the scat rotating assembly - Competition products out of Oshkosh WI

with your motors being MPI, you will need a reprogram of the ECM