Engine swap question

[sardonicus]

Hello again folks, got a new boat to ask about. I have 78 slick craft 20 footer, numbers found on the valve cover 4942063, the I/O sterndrive is a mercruiser 898. Everything I've found thus far tells me the V8 in this thing is a 305, sadly the block is cracked so its scrap, but all the manifolds are still good the carb is still good, all those wonderful marine only parts seem to be undamaged. So my big question, can I put all this stuff on a Chevy 350? I might have one available to me on the cheap thats still running. If I missed anything vital that you guys need to help me out just let me know and I'll do my best to get the information posted.

 

[Bondo]

Re: Engine swap question

Hello again folks, got a new boat to ask about. I have 78 slick craft 20 footer, numbers found on the valve cover 4942063, the I/O sterndrive is a mercruiser 898. Everything I've found thus far tells me the V8 in this thing is a 305, sadly the block is cracked so its scrap, but all the manifolds are still good the carb is still good, all those wonderful marine only parts seem to be undamaged. So my big question, can I put all this stuff on a Chevy 350? I might have one available to me on the cheap thats still running. If I missed anything vital that you guys need to help me out just let me know and I'll do my best to get the information posted.

Ayuh,.... Welcome Aboard,.... If yer donor motor is of the same vintage,... Yes...

otherwise there'll be adaptin' to do...

 

[achris]

Re: Engine swap question

I'll just clarify a few things for you, so you don't get confused...

The engine is a Mercruiser '898', a 305 SBC V8, 198hp... The drive is an MC-1. The decal on the drive that says '898' is the engine designator, not the drive model...

When you get the 350, make sure it has brass core plugs, and a marine cam (believe it or not the cam from the 305 is the same as the one used in the marine 350, so you can even pull that one out of the broken 305), and if you put a 4bbl Carbie on (and manifold), you'll have a full 260hp engine... The carbie I'd recommend is the Edelbrock 1409 (http://www.summitracing.com/parts/EDL-1409/)

Just one thing... The 898 ran a 1.65:1 drive ratio, and the 350s usually used a 1.5:1. You will need to run a higher pitch prop, or change the ratio/drive if the pitch gets too high (more than about 23")...

Chris.......

 

[sardonicus]

Re: Engine swap question

Excelent information! Thank you very much, glad to finally have something easy. How important is the marine cam? If I do have to get an adapter, which is possible I don't have a lot of info on my possible donor motors yet, where would I look for something like that? I haven't looked yet but did the 305s by default have 2bbl carbs on them? Thanks again for the information! Very helpful!

 

[achris]

Re: Engine swap question

Excelent information! Thank you very much, glad to finally have something easy. How important is the marine cam?

Very... If you want the boat to be 'driveable' then you need a cam with as flat a torque curve as you can get... No gears in a boat like a car, so the engine has to be able to pull from as low down as possible...

If I do have to get an adapter,

Not an adapter, adapting... You will be doing some adapting...

which is possible I don't have a lot of info on my possible donor motors yet, where would I look for something like that?

You have the year of the 898, 1978, so if the 350 is around the same era, then it should be a straight swap..

I haven't looked yet but did the 305s by default have 2bbl carbs on them? Thanks again for the information! Very helpful!

Yes, the 898 was a 2bbl carbed 305 engine... The same engine with a 4bbl was a '228' (228hp)...

Chris.....

 

[sardonicus]

Re: Engine swap question

Could you elaborate on adapting for me? I have some basic knowledge about how this stuff works, and what goes where, just not enough that I really know where to look to do anything over and above general maintenance and repairs.

 

[franktrav]

Re: Engine swap question

the drive couplers for an engine with a 2 piece rear main seal, and a 1 piece seal are different.....if your replacement engine is not the same vintage as your old one......you may need a new coupler

 

[achris]

Re: Engine swap question

Could you elaborate on adapting for me? I have some basic knowledge about how this stuff works, and what goes where, just not enough that I really know where to look to do anything over and above general maintenance and repairs.

Hard to say without seeing the 2 engines sitting next to each other... And it depends on the era of the 350....

 

[sardonicus]

Re: Engine swap question

I understand, once I get the donor, I will post more information on it to revisit this question. Thank you to everyone that responded to this post for the information, I am well on my way to the right track thanks to you guys.