Replacing my motor..help with getting new one..

[New_Blue]

Hi all,

I have heard that boat ownership can be a journey and until recently I really didn't know what that meant...now i do. I found out my new to me boat has a cracked block and due to the age of the thing (1979Searay with Mercruiser 898(Chevy 305)) and my limited experience with boat motors I am going to take the plunge and swap the whole thing out with a dressed motor.

How do I make sure what I am ordering matches what I really need. This is where my stomach starts churning...Momma would have me on the couch for a YEAR if I screw this up! :redface:

Should I swap the 305 with 350 (I can't see why i wouldn't want more horsepower) or are there considerable drawbacks?

Are there reputable places you could recommend that will take the time with someone new to boats like me that?

Thank you for your help!

 

[Fishermark]

Re: Replacing my motor..help with getting new one..

How do I make sure what I am ordering matches what I really need. This is where my stomach starts churning...Momma would have me on the couch for a YEAR if I screw this up! :redface:

Should I swap the 305 with 350 (I can't see why i wouldn't want more horsepower) or are there considerable drawbacks?

Are there reputable places you could recommend that will take the time with someone new to boats like me that?

Thank you for your help!

If you are simply replacing the block - or the short block, then you will want to stay with a block like yours. In other words, if yours has the two piece rear main seal, and I believe it does, then that is the kind of engine you want to buy.

Not many reasons to avoid the 350 - and many good reasons to go with it - you won't be sorry.

Some will recommend various rebuilders. I personally would suggest buying a new engine - you can get some good deals straight from Chevy - whether buying a short block, long block, or complete engine.

NOW IF YOUR EXTERNALS ARE BAD - meaning your manifolds, etc. You might want to look into buying a complete "Bobtail" ready to drop in engine.... but that's a lot more money. Worth looking into if your misc parts are all shot.

Good luck!

 

[Fishermark]

Re: Replacing my motor..help with getting new one..

GM Universal 350 - new crate engine. Part number 10067353

You can pick it up at various places for under $1,600

 

[Bondo]

Re: Replacing my motor..help with getting new one..

and my limited experience with boat motors I am going to take the plunge and swap the whole thing out with a dressed motor.

Ayuh,... New,..?? From Mercruiser,..??

As long as you have the old motor, complete, you'll have All the pieces to marry the New, to the old...

If your accessories are all still Good,... Mark's Idea is a Great way to go....

 

[New_Blue]

Re: Replacing my motor..help with getting new one..

That's the tough part for me...I was told by a mechanic that the parts on the motor(besides the block) have an average life of 10 years. Plus the exhaust manifolds are cracked in a couple of places. If this is a 30 year old motor then wouldn't most of the components be ready for the dump? However, one of the reasons I liked the boat was that it had 180 hours on the meter...if I am to believe that....

I thought all motors had to be marine motors? Can you really use a car long block and put marine water pump, exhaust manifolds, distributor etc on it? I thought that marine blocks had the correct bolt holes and things to mount marine components....

Thank you for all the help!

 

[IVAZ]

Re: Replacing my motor..help with getting new one..

I thought all motors had to be marine motors? Can you really use a car long block and put marine water pump, exhaust manifolds, distributor etc on it? I thought that marine blocks had the correct bolt holes and things to mount marine components....

These guys are giving you good advice.
The holes to bolt your marine stuff are already on that new block. I might be wrong but I think these new block already have the brass core plugs and the proper headgasket. I have heard that some people even use them with the truck cam. Someone here will correct anything that was incorrect on my part.

 

[flargin]

Re: Replacing my motor..help with getting new one..

I liked the boat was that it had 180 hours on the meter...if I am to believe that....

I am sure the hour meter was only 180 hours old

 

[New_Blue]

Re: Replacing my motor..help with getting new one..

One last question to make sure i am reading this right...so I can buy a 350 long block and attach my 305 carb, fuel pump, intake manifold, dist cap etc with no worries. I guess i thought the bigger bore would require upgraded externals....

Thank you for your help/patience...

 

[IVAZ]

Re: Replacing my motor..help with getting new one..

One last question to make sure i am reading this right...so I can buy a 350 long block and attach my 305 carb, fuel pump, intake manifold, dist cap etc with no worries. I guess i thought the bigger bore would require upgraded externals....

Thank you for your help/patience...

The carb might not be jetted for optimal performance on a 350 but thats minor. Everything else will bolt up just fine. The 350 and 305 are basically the same engine except the 350 has a bigger bore.

 

[kevincave]

Re: Replacing my motor..help with getting new one..

in my experience with cars and boats, the 350 will use a little more fuel than the 305. and i have had several of the motors. you absolutely cannot go wrong with the g.m. crate motor.......

 

[HT32BSX115]

Re: Replacing my motor..help with getting new one..

Plus the exhaust manifolds are cracked in a couple of places.

Of course, you'll have to replace your manifolds, risers, (you might even need a new intake manifold)

If your starter, alt, power steering pump are ok, you can use them. I would replace the fuel pump and the water pump though...

 

[mkast]

Re: Replacing my motor..help with getting new one..

If this is a 30 year old motor then wouldn't most of the components be ready for the dump?

Send the marine starter and alternator out for rebuilding.
New marine water pump and exhaust system.
You didn't mention if you had a two or four barrel carburetor?
Fresh water or salt operation?
What type ignition does a 79' use?

 

[Fishermark]

Re: Replacing my motor..help with getting new one..

so I can buy a 350 long block and attach my 305 carb, fuel pump, intake manifold, dist cap etc with no worries.

Yep.

The only "worry" is their condition, not whether or not they will fit. They will bolt up and work just as well on the 350 as the 305. That's the beauty of Chevy engines.

You might want to take an awl or something and scratch the paint from the core or freeze plugs and make sure they are brass, not steel. If they are steel, change them out - easy to do. If they are brass, then you are good to go.

I wouldn't worry about the carb being any different for the 305 to 350 change.

 

[MikDee]

Re: Replacing my motor..help with getting new one..

Yep.
I wouldn't worry about the carb being any different for the 305 to 350 change.

All good info here, and I agree, I wouldn't worry about the carb either!

I suggest you go with a 350, You won't be sorry! It'll fit like a glove, and be an immediate 30hp more, without using that much more fuel.

You can never have too much horsepower!

 

[Gary H NC]

Re: Replacing my motor..help with getting new one..

The new motor and an exhaust manifold complete kit from ebasicpower.com
You will be good to go...