Help Please. Mercruiser 305 to Mercruiser 351

[Mikeyd0703]

Hey guy im a little new to this so im sorry. I have a 1992 Larson Hampton with a Mercruiser V8 5.0 305 with a cracked block. I purchased a Mercruiser V8 351 233L and was wondering what i need to make this work. I have a Alpha one Gen II outdrive. Some people are telling mixed things. People are telling me i need a new bell housing and some people are telling me i need a new engine. Is there any way possible i can make this work? please let me know because i am desperate to get my dad out on to the water. I tried looking at threads and had no luck. Thanx to all in advance.

 

[Eric 3.7LX Alpha 1]

Re: Help Please. Mercruiser 305 to Mercruiser 351

Well I believe the 305 is a Chevy block and the 351 is Ford. 350 would have been easier. Bolt patern is going to be different for the belhousing, as well as some other parts.

 

[JustJason]

Re: Help Please. Mercruiser 305 to Mercruiser 351

If you can't answer this question by all means post a few pictures of the old and new motors.
Do you know positively if you have a GM/Chevy 5.7 liter 350 cubic in block. Or do you have a Ford 351 block? If it's a ford, do you know if it's a Windsdor block or a Cleveland block? Where did you purchace it... and what did it come out of?

 

[Bondo]

Re: Help Please. Mercruiser 305 to Mercruiser 351

I purchased a Mercruiser V8 351 233L and was wondering what i need to make this work. I have a Alpha one Gen II outdrive.

Ayuh,... No Way, No How will that ever happen...
I don't believe there was Ever the flywheel cover to do it...

You need a 350 Chevy long block,+ reuse the other parts off your 305....

 

[Mikeyd0703]

Re: Help Please. Mercruiser 305 to Mercruiser 351

Hey guys thanx for the replies.. I know its a Chevy 305 i have in the boat now.. the other engine i just purchased is a 351 windsor engine. It sux cause this engine is in mint condition and i really wanna put it in lol.. I purchased it from someone on craigslist and it came out of a betram boat is what the previous owner told me.

 

[haulnazz15]

Re: Help Please. Mercruiser 305 to Mercruiser 351

The issue he'll have is going to be the inner transom plate. While you could get one for a 351/alpha I or Volvo outdrive, they didn't make any 351's with the Alpha II outdrive. The easiest thing is going to be selling the 351w (Ford) and getting a 350 (chevy). Otherwise, you'd be out looking to swap to an Alpha I or Volvo transom/outdrive setup which is much more expensive and difficult to swap.

 

[haulnazz15]

Re: Help Please. Mercruiser 305 to Mercruiser 351

Or do you have a Ford 351 block? If it's a ford, do you know if it's a Windsdor block or a Cleveland block?

I don't believe I've ever heard/seen a 351C in a marine application before. Maybe a direct-drive or custom build, but not likely mated to a I/O.

 

[Mikeyd0703]

Re: Help Please. Mercruiser 305 to Mercruiser 351

so if i get a new ourdrive for it wouldnt i just need a new inner transom plate? im sure i can get 1 off of craigslist that would work. or im just hoping it would work. I have the engine on craigslist for $1000.00 and i paid $1300 for it. I have someone who has a 305 crusader or a 4.3 L Mercruiser vortec. People are saing they will fit but what do i know lol.

 

[haulnazz15]

Re: Help Please. Mercruiser 305 to Mercruiser 351

You would need a new outdrive, with inner transom plate and bell housing to match (either volvo or Alpha I/Pre-Alpha). The wiring for the Volvo could be a small issue compared to what you already have with the Merc setup. Lots of gaskets and things would need to be replaced as well as messing with the trim setup.

Long story short, getting a 305/350 would be your best move. You can go to a 4.3L too, but if you're messing with it, I'd get the 350 and be done with it. More HP, more TQ, same parts to swap over. I'm amazed that you paid $1300 for a 233 (351w) since that engine was made/used from about 1975-78. Sell it for what you can get out of it, and get a new long block from Rapido or other reputable dealer and swap your stuff over from the 305.

 

[dirtyoldman]

Re: Help Please. Mercruiser 305 to Mercruiser 351

I don't believe I've ever heard/seen a 351C in a marine application before. Maybe a direct-drive or custom build, but not likely mated to a I/O.

I agree. The Cleveland and M blocks had a different bolt pattern to match the 385 series engines.

 

[JustJason]

Re: Help Please. Mercruiser 305 to Mercruiser 351

I don't believe I've ever heard/seen a 351C in a marine application before. Maybe a direct-drive or custom build, but not likely mated to a I/O.

Neither have I, but I was just asking. Who knows what people pull out of bone yards these days. He's already up ships creek with the 351, but if he had a cleveland he'd be up ships creek without a paddle.

 

[Mikeyd0703]

Re: Help Please. Mercruiser 305 to Mercruiser 351

Hey guys i just wanna thank you all for your help. All of you on here are a blessing helping people like me out. I have someone who owns a boat with twin 351 motors and he has a 305 engine with outdrive to swap out for me. He said he put diesel fuel in it to lubricate it.. is that good? or bad? he said i would need to just change the plugs and thats all. He said this will be a good backup for him. Im figuring this is a good swap. Your input will help me more. Thanx again all of you who took the time to come on here and help me out. I found a good website !!!!

 

[John_S]

Re: Help Please. Mercruiser 305 to Mercruiser 351

Make sure that 305 is the same vintage as yours. ie post '87. One piece oil seal, center-bolt valve covers, etc. The main thing will be same flywheel, starter, and coupler, though.

 

[JustJason]

Re: Help Please. Mercruiser 305 to Mercruiser 351

What do you mean diesel fuel to lubricate it???

 

[Mikeyd0703]

Re: Help Please. Mercruiser 305 to Mercruiser 351

Thats what he told me. I guess he put diesel fuel in the lines. He told me all i have to do is change the plugs and give it a tune up. Is there a way i can see if it is the same exact vintage as mine? I know mine is a 1992 Mercruiser 5.0. Will the serial numbers tell me?

 

[John_S]

Re: Help Please. Mercruiser 305 to Mercruiser 351

Is there a way i can see if it is the same exact vintage as mine? I know mine is a 1992 Mercruiser 5.0. Will the serial numbers tell me?

If it has mercruiser serials numbers. If it hasn't been messed with, having center-bolt style valve covers, would be a good indication.

 

[Mikeyd0703]

Re: Help Please. Mercruiser 305 to Mercruiser 351

Will a OMC 5.0 V8 Complete with complete Outdrive for on my 1992 larson hampton 220? I have someone who is selling it and would like to know if this will work. I have in my boat now a Mercruiser 5.0 305 chevy.. Thanx all