Replacing 93 305 Mercruiser

[Biggyniner]

Hey All,

I need to replace the engine in a 93 Ciera. It has a 305 Mercruiser and I'm going to drop a 350 long block in it and transfer the tins, intake, carb, etc. over. I found Jegs and Summit both have basic 350 long blocks for about 1600. Summit also had a "Marine 350" for $1900. My question is what is different? The listing says Marine Pistons, Marine gaskets, etc... Is that bunk or are there really differences in the gaskets between auto and marine? If it makes any difference I plan on running a full closed cooling system.

Thanks for any insight!

Here is the link to the summit "Marine" engine:

 

[thumpar]

The head gaskets will use stainless in them. The core plugs will be brass or stainless.

 

[Biggyniner]

The head gaskets will use stainless in them. The core plugs will be brass or stainless.

Gotcha, good to know!

 

[Scott06]

Camshaft will be different between an auto and marine. Generally a truck cam and marine are regarded as interchangeable/ same/close enough. As mentioned above core plugs, head gaskets, and water pump are different as well

 

[Biggyniner]

The head gaskets will use stainless in them. The core plugs will be brass or stainless.

Do you think that matters if I am running cull closed loop cooling?

 

[alldodge]

Do you think that matters if I am running cull closed loop cooling?

Not as much, you should be good with closed cooling. Now if your in salt water, the core plugs could rust from the outside if not protected.

Don't use the 305 carb on the 350 without looking into the correct jet size

 

[Biggyniner]

Not as much, you should be good with closed cooling. Now if your in salt water, the core plugs could rust from the outside if not protected.

Don't use the 305 carb on the 350 without looking into the correct jet size

Gotcha, Thanks... Primarily freshwater usage so I think I will get the truck engine.

 

[thumpar]

Gotcha, Thanks... Primarily freshwater usage so I think I will get the truck engine.

Just keep in mind the warranty will be voided if you do that.

 

[Scott Danforth]

I would go with a vortec headed motor and get a different intake

 

[Biggyniner]

I would go with a vortec headed motor and get a different intake

The transom has a sticker that says 230 HP max, I think the vortec would far exceed it lol

 

[thumpar]

The transom has a sticker that says 230 HP max, I think the vortec would far exceed it lol

You will be at 260hp with a 350. I have never seen an I/O with a HP rating. Even if it had one I would ignore it, especially in that boat. I would bet it cam with more power as an option.

 

[Biggyniner]

You will be at 260hp with a 350. I have never seen an I/O with a HP rating. Even if it had one I would ignore it, especially in that boat. I would bet it cam with more power as an option.

According to the brochure there were two options at the time.

The 305 was putting out ~210 HP
The 350 option ~230 HP

But yea I figure I would be a little over

 

[Scott Danforth]

Col regs for hp do not apply to I/O's, only outboards

however its your boat do what you want.

Me, I would build a new stroker motor for a few hundred more than your paying for the remaned ATK motor

 

[Biggyniner]

Col regs for hp do not apply to I/O's, only outboards

however its your boat do what you want.

Me, I would build a new stroker motor for a few hundred more than your paying for the remaned ATK motor

Well that's an intriguing thought...

 

[achris]

... I have never seen an I/O with a HP rating. Even if it had one I would ignore it, especially in that boat. I would bet it cam with more power as an option.

Now, are you referring to a hull having a maximum power rating? If so, every boat, be it an I/O or an outboard, BY LAW must be tagged with a maximum horsepower and a maximum load rating.

If you're talking about the engine itself... Umm, yeah, they ALL come with a rated horsepower....

Either way, ya talkin' garbitch!

AND, ignore the ratings at your peril.... Something bad happens (an accident) and two much worse things will happen. First, that is the door your insurance company will walk out on you through. Second, it's the door the USCG and any plaintiffs (and their teams of lawyers) will walk IN through, and string you up so tight you'll never own anything again, ever!

Play by the rules people....

Chris......

 

[Scott Danforth]

Chris, you need to check the col regs (uscg). HP limits only apply to outboard power

iBoats has the link to the whole USCG boat builder regs.

 

[thumpar]

Now, are you referring to a hull having a maximum power rating? If so, every boat, be it an I/O or an outboard, BY LAW must be tagged with a maximum horsepower and a maximum load rating.

If you're talking about the engine itself... Umm, yeah, they ALL come with a rated horsepower....

Either way, ya talkin' garbitch!

AND, ignore the ratings at your peril.... Something bad happens (an accident) and two much worse things will happen. First, that is the door your insurance company will walk out on you through. Second, it's the door the USCG and any plaintiffs (and their teams of lawyers) will walk IN through, and string you up so tight you'll never own anything again, ever!

Play by the rules people....

Chris......

There is no max HP rating on my tag only weight and people. I am pretty sure my previous boat was the same way. They have them on outboard equipped boats but not I/Os, at least here in the US.

 

[Biggyniner]

I'll see if I can snap a pic, so y'all don't think I'm Crazy

 

[Rick Stephens]

I'll see if I can snap a pic, so y'all don't think I'm Crazy

YOU OWN A BOAT!

You cannot prove sanity at this point in your debacle.

 

[Scott Danforth]

You own a bayliner, they had both outboard models and IO models. It is likely the incorrect capacity tag is on the boat from the factory