convert 3.0L Mercury to SBC

[benblank]

I have the opportunity to purchase a 95' Wellcraft Eclipse with a cracked 3.0L Merc block. I like the idea of converting it to a SBC (350ci most likely) rather than replacing the block.

The boat currently has a Volvo SX outdrive, I have never have worked on a boat myself but am very familiar with SBC's my question is what I am getting myself into?

 

[maxxman04]

Re: convert 3.0L Mercury to SBC

alot of work, alot of money. stringers to fit the 350 motor mounts might need to be glassed in. gear ratio in the outdrive won't work with a 350. exhaust, motor mounts, manifolds. for starts. unless you can find another donor boat for cheap, might be best to find a good running 3.0L to replace cracked one.

 

[benblank]

Re: convert 3.0L Mercury to SBC

alot of work, alot of money. stringers to fit the 350 motor mounts might need to be glassed in. gear ratio in the outdrive won't work with a 350. exhaust, motor mounts, manifolds. for starts. unless you can find another donor boat for cheap, might be best to find a good running 3.0L to replace cracked one.

Thanks for the reply, I figured it would be alot. For the exhaust couldn't I do some kind of through hull setup? I was thinking of running an LT1 out of the Camaro/Corvette so it would be fuel injected. But it sounds like a lot of work just to get the motor mounted into the boat and to get the outdriving working.

 

[maxxman04]

Re: convert 3.0L Mercury to SBC

alot of work, yes. thru hull exhaust is an option. the 3.0L outdrive would need gear changes, easier, probably cheaper, to pickup outdrive with correct gearing. still easier to find a donor boat, maybe minus motor, but with right outdrive and such, swap them over.

 

[maxxman04]

Re: convert 3.0L Mercury to SBC

also, i may be wrong, but you may run into issues properly "marinizing" an LT1. generally the starter, alternator, distributor should be marine grade as they are built to resist moisture corrosion. it may not be impossible, as parts might be available, but to just drop in the automotive version and go isn't a good idea. fumes can build up under engine cover, and even running the blower may not get all the vapors out. remaining vapors can be sparked by a non sealed distributor, as an example. might research to see what is available to make an LT1 marine safe.

 

[benblank]

Re: convert 3.0L Mercury to SBC

also, i may be wrong, but you may run into issues properly "marinizing" an LT1. generally the starter, alternator, distributor should be marine grade as they are built to resist moisture corrosion. it may not be impossible, as parts might be available, but to just drop in the automotive version and go isn't a good idea. fumes can build up under engine cover, and even running the blower may not get all the vapors out. remaining vapors can be sparked by a non sealed distributor, as an example. might research to see what is available to make an LT1 marine safe.

The biggest thing for me is the mounts for the SBC. I do not know how to fiberglass for starters. For the outdrive being the wrong gearing, is that something you could take to a typical marina to have them change the gearing?

 

[maxxman04]

Re: convert 3.0L Mercury to SBC

The biggest thing for me is the mounts for the SBC. I do not know how to fiberglass for starters.

i'd suggest finding a qualified 'glass man for this. not for the novice.

For the outdrive being the wrong gearing, is that something you could take to a typical marina to have them change the gearing?

i'd check out marinas to find a qualified SX mech. also verify cost versus buying a new or even used one. gear change can be done, but yes, should be left to those who know how. prepare yourself for a bit of sticker shock tho to have yours regeared.