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305 Mercruiser froze and busted block this winter

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ctrot20

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Ok guys I need help, my 2000 model Larson ski boat has a 305 5.0 Mercruiser engine that froze and busted this past winter. I'm thinking about buying a 95 model 350 out of a Chevrolet truck to replace it. What all will I need to do to make this work in my boat????
 
I was told to buy a marine engine but I do not see why you could not make it work but saving a little up front may cost you more in the long run.
 
I was told by many mechanics that a vehicle engine will be lucky to last 6 months as they do not run WOT all the time a marine engine is much stronger for the long high rev running conditions
You may get one cheap but be disapointed when it doesn't last
Just some thought before doing this ...read up on it you will get the info you need from other members who know whats wot
I thought of doing the same thing
 
Actually.... a marine engine won't last all that long running @ WOT either. For any kind of decent engine life, you should limit continuous engine RPMS to a maximum of 80% of the maximum WOT RPMs ( assuming you have a prop that limits such RPMs to within the manufacturer's specified MAX RPM range).

The differences between an auto engine and a marine engine are too numerous to list totally here, but include: cam type, materials used in the cooling system, and for some engines the type of piston head. This is in addition to the fact that the carb ( or injection system), distributor, alternator, starter all need to be USCG approved for marine use.

If you are on a tight budget, get a reman from a REPUTABLE source. IF your "accessories" are in good shape ( did the exhaust manifold crack as well?), get a long block. When faced with replacing the 30+ yo raw water cooled engine in my boat when I bought it, I elected for a brand new all up MERCRUISER with a FWC kit.

My time and aggravation are worth money to me. A boat sitting in a slip in season, not running, on one of the relatively few days I have available to use my boat in any given season, is a HUGE issue for me.
 
Last edited:
ctrot20 said:
Ok guys I need help, my 2000 model Larson ski boat has a 305 5.0 Mercruiser engine that froze and busted this past winter. I'm thinking about buying a 95 model 350 out of a Chevrolet truck to replace it. What all will I need to do to make this work in my boat????
Click to expand...

Ayuh,.... Go for it, it's done All the time,....

Yer intake won't swap over though,... The bolt pattern is different,...
You'd need a '96, 'n up 350,.... aka: Vortec heads,...
 
bondo said:
Ayuh,.... Go for it, it's done All the time,....

Yer intake won't swap over though,... The bolt pattern is different,...
You'd need a '96, 'n up 350,.... aka: Vortec heads,...
Click to expand...

I agree, I also agree with purchasing a Marine remanufactured motor also BUT,

Gm (or whom ever is contracted to) manufactures the basic truck block 305/350 (220 hp/260 hp +/-) and when it goes down the assembly line the marine go left and the automotive goes right. The long block guts (pistons/cams/etc) are the same with the exception of:

The left line adds bronze core plugs and marine head gaskets, marine oil pump (brazed oil pump tube and specific to oil pan and most will also have a windage tray attached to the main bolts ) and oil pan assembly and a bidirectional bronze impellered engine water pump and (for carbed motors) a non emission intake and carb. Not sure if they install starter, alt, ignition at the assembly plant or not but if they do then it is marine specific.

I may have missed a few but you get the idea.

As Bondo said there are differences between the years you are dealing with SO, if you be sure they are the same core block (intake and one piece rear main seal, etc etc... then you can simply swap all the marine parts including the oil pump assembly!!
 
kghost said:
I agree, I also agree with purchasing a Marine remanufactured motor also BUT,

Gm (or whom ever is contracted to) manufactures the basic truck block 305/350 (220 hp/260 hp +/-) and when it goes down the assembly line the marine go left and the automotive goes right. The long block guts (pistons/cams/etc) are the same with the exception of:
Click to expand...


"TRUCK BLOCK" are the important words here.
 
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