What's the difference really? I've heard it was just freeze plugs. I got to thinking, my dads been wanting to put a bigger engine in his boat for a while and give me the Mercruiser 350 Mag to use in a car. Would it work in say my 77 Camaro over my 307 Chevy?
IIRC... Marine spec intake(containing backfire), packaging differences(typicaly more room in the boat than a car), dual engine boats have one running reverse rotation, Different power band(low end, slow throttle response).
Maybe?
If it has all the same external mounting points as a auto based 350 chevy, a cam and intake should make it steetable.
Boat engines get run a lot harder than even a race car engine - flat out at high revs with zero breaks for indefinite periods of time. So you'll need a much better cooling system for one thing.
I imagine the cams/tune for powerband is very different due to the way they get used. You don't vary throttle in a boat often - you push the lever until you get the RPMs you need and leave it there for long periods. It makes me wonder why they aren't all turbo diesel powered.
I also guess the water pump is different, possibly external and electric so you can flush sea water out without starting the boat on land.
A boat is designed to have lots of grunt and peak out fairly low, think truck engine, though they are also typically high compression and built to be very durable, if disappointing as is, a cam would definitely fix it.
Well I got to reading the specs on the 350 Mag MPI, it tops out around 5,000 rpm with 300 horsepower. Which, if my dyno program is accurate, is what my 307 should be capable of doing the way I'm building it
It will be a lot more work to make a 307 do that. Remove all the boat crap and you've basically got a fairly mild vortec headed roller cam 350.
GameboyRMH wrote: Boat engines get run a lot harder than even a race car engine - flat out at high revs with zero breaks for indefinite periods of time. So you'll need a much better cooling system for one thing.
and there you have the general difference #2......alot of boats have unlimited cooling systems
Kenny_McCormic wrote: It will be a lot more work to make a 307 do that. Remove all the boat crap and you've basically got a fairly mild vortec headed roller cam 350.
Heads, cam, intake, exhaust in the 307. But I'm also beginning to wonder since boat engines are meant to be raped upon, what's the likelihood of it being a 4 bolt main?
As for power band, I've never tried on in a car. I know they will run wide open all day, but are also happy cruising along at any other speeds. Pulling skiers you'll go from idle to full throttle and then back off to the desired speed depending on slolom, two skis, wakeboard, kneeboard, or tube and then hold that steady for as long a needed.
Based on what I have seen and worked (mainly OMC) the differences are:
Freeze plugs, gaskets ( especially head, intake and exhaust for better corrosion resistance), thermostat housing (eztra bypass outlets to exh manifold), distributor and coil (mine was an '88 and it used a prestolite points distributor with external coil), oil pan and dipstick tube (dipstick tube was connected to oil pan drain so you could suck the oil out through the tube for changes), exhaust manifolds (watercooled), brass plugs (freeze and drain), waterpump (material change, but will work for auto).
All electrical accessories and the air cleaner had spark arrestors (basically screen inside the vents on the accessories).
I'd been told the crank was steel, but never had a need to confirm that. Also they will typically have a standard flywheel painted to prevent rust.
Most boats have HD items like 4 bolt mains, forged cranks etc.
It will not be working as hard as the 307 to make 300hp. If the boat was on fresh water I wouldn't worry about it to much. If it spent much time in salt water forget it. Growing up on Long Island I can count on no hands the number of clean boat engines I've seen.
In reply to Wally: I live in the middle of Missouri. I'm too far away to have a saltwater boat so I'm good.
If there's even a chance of 4 bolt mains and a forged crank I think I'll use it in my Camaro
Its almost guaranteed to be 4 bolt mains and guts good for plenty of power.
Kenny_McCormic wrote: Its almost guaranteed to be 4 bolt mains and guts good for plenty of power.
So you think it'd be good for a turbo if the compression is low enough?
Wally wrote: It will not be working as hard as the 307 to make 300hp. If the boat was on fresh water I wouldn't worry about it to much. If it spent much time in salt water forget it. Growing up on Long Island I can count on no hands the number of clean boat engines I've seen.
This has more to do with whether the engine used a "closed cooling" system or an "open cooling" system.
Closed means it's just like a car setup, except instead of air and a radiator, there was a heat exchanger that pulls the water in and removes heat and then dumps it.
An open system just runs whatever water the boat is in through the engine itself.
In reply to DCharger68:
Odds are its going to have compression in the 9s or higher.
Wally wrote: It will not be working as hard as the 307 to make 300hp. If the boat was on fresh water I wouldn't worry about it to much. If it spent much time in salt water forget it. Growing up on Long Island I can count on no hands the number of clean boat engines I've seen.
x2 someone gave me 454 heads from a boat that had seen saltwater. i promptly took out all the nice valves and springs and scrapped the castings, they were flaking off in chunks inside the coolant passages.
Giant Purple Snorklewacker wrote: I imagine the cams/tune for powerband is very different due to the way they get used. You don't vary throttle in a boat often - you push the lever until you get the RPMs you need and leave it there for long periods. It makes me wonder why they aren't all turbo diesel powered. I also guess the water pump is different, possibly external and electric so you can flush sea water out without starting the boat on land.
Or rotary :)
fidelity101 wrote:Giant Purple Snorklewacker wrote: I imagine the cams/tune for powerband is very different due to the way they get used. You don't vary throttle in a boat often - you push the lever until you get the RPMs you need and leave it there for long periods. It makes me wonder why they aren't all turbo diesel powered. I also guess the water pump is different, possibly external and electric so you can flush sea water out without starting the boat on land.Or rotary :)
Me and my college roommate discussed this idea many times
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