Boat People - Marine engines

[larboc]

FYI there a ton of sub $1k L31's on car-part.
Autozone has no-name rebuilt long-blocks for sub $1800. Make sure whatever you get has a mechanical fuel pump boss for it if you can. That could be the only gotcha. Mech. pumps in a boat are the way to go IMHO. Not sure if an L31 would have the mech pump drive.

 

[arse_sidewards]

Nothing. I ran the numbers on a mercruiser 350 I pulled a few years ago and it was just some random truck block.

The literal block is almost always a normal OEM block.

Often times on older shit with shitty low compression iron heads you'll see wacky piston choices because not being beholden to road emissions standards they were able to get away with dialing the compression a notch.

That said, for what OP is doing just about anything that bolts in should work well enough after he tosses his cam and lifters in it.

 

[Whistlepig]

Honestly I have seen a few people fix water jacket blowouts with jb weld and a hammer and it worked fine. Did the manifolds survive?

The manifolds are good. The jb weld did cross my mind as well as tig welding them with 309 but I would sure like to not pull this engine again if it doesn’t hold.

 

[Whistlepig]

FYI there a ton of sub $1k L31's on car-part.
Autozone has no-name rebuilt long-blocks for sub $1800. Make sure whatever you get has a mechanical fuel pump boss for it if you can. That could be the only gotcha. Mech. pumps in a boat are the way to go IMHO. Not sure if an L31 would have the mech pump drive.

Mine is mpi so it has a water cooled electric pump.

 

[larboc]

The manifolds are good. The jb weld did cross my mind as well as tig welding them with 309 but I would sure like to not pull this engine again if it doesn’t hold.

These guys didn't even pull it. Carb cleaner, JB weld, hammer, wait overnight and go boating. Freeze damage happens in places that aren't under much stress as long as it's not below freezing again. Also, a small leak isn't the end of the world with a raw water cooled engine, you can get it home and slap some flex seal on it.
If you're pulling it, weld it up and leak test on the stand with a hose.

Check the transom thoroughly for any rot as soon as you pull the engine before you get too far. Consider gimble bearing, bellows, and drive coupler while the engine is out. Order up an alignment tool if you don't have one.

 

[sicumminsde]

I know on some boats with I/O, they have a heat exchanger set up. They use standard coolant in the engine and it is pumped through a separate heat exchanger. This keeps the salt water out of the engine block.

 

[larboc]

I know on some boats with I/O, they have a heat exchanger set up. They use standard coolant in the engine and it is pumped through a separate heat exchanger. This keeps the salt water out of the engine block.

Uncommon, but a better way to do it. They can also run a hotter thermostat which is better for the engine.
More expensive, harder to package, heavier, hence less common. IIRC 470's were all that way.

 

[arse_sidewards]

Uncommon, but a better way to do it. They can also run a hotter thermostat which is better for the engine.
More expensive, harder to package, heavier, hence less common. IIRC 470's were all that way.

I wouldn't call it uncommon. It's basically SOP with saltwater inboards and I/Os these days though I suspect you see a different spread of configurations on the great lakes. You're right about 470s all being that way. They're basically ancient history around here though.

 

[NT2HLBLY]

Almost zero pressure on the cooling system. JB weld and roll. A little leakage is for the bilge pump.

To answer your question. Marine uses different freeze plugs and always a different cam. Car or truck cams have to much overlap and you can suck in water through the exhaust. I have a truck block in my 88 Rinker with the previously mentioned shit swapped oh and a marine carb.

 

[Whistlepig]

Almost zero pressure on the cooling system. JB weld and roll. A little leakage is for the bilge pump.

To answer your question. Marine uses different freeze plugs and always a different cam. Car or truck cams have to much overlap and you can suck in water through the exhaust. I have a truck block in my 88 Rinker with the previously mentioned shit swapped oh and a marine carb.

The only problem is all three cracks are under the intake which would go straight to the oil pan and I cant keep an eye on it.

These guys didn't even pull it. Carb cleaner, JB weld, hammer, wait overnight and go boating. Freeze damage happens in places that aren't under much stress as long as it's not below freezing again. Also, a small leak isn't the end of the world with a raw water cooled engine, you can get it home and slap some flex seal on it.
If you're pulling it, weld it up and leak test on the stand with a hose.

Check the transom thoroughly for any rot as soon as you pull the engine before you get too far. Consider gimble bearing, bellows, and drive coupler while the engine is out. Order up an alignment tool if you don't have one.

Transom is solid. I do have to replace the bellows and gimble bearing. Coupler is good also.

 

[Chevy_man]

Found out what I was thinking about. Intakes with brass lined water passages.

Performer RPM Vortec Marine Intake Manifold Small-Block Chevy

Performer RPM Q-JET Marine Intake Manifold For 1996+ Small-Block Chevrolet 262-400 V8's with E-Tec or Vortec Heads. Cooling Water Passages are Lined with Brass to Prevent Corrosion. Carb Pads Accept Q-Jet or Square-Bore Marine Carburetors

www.compcams.com

This getting old thing, I'll be damned if my brain doesn't get lost sometimes.



I'd love to find these $1k L31s. Yards around here want $2500 for a running one with compression over 150.

 

[larboc]

Found out what I was thinking about. Intakes with brass lined water passages.

Performer RPM Vortec Marine Intake Manifold Small-Block Chevy

Performer RPM Q-JET Marine Intake Manifold For 1996+ Small-Block Chevrolet 262-400 V8's with E-Tec or Vortec Heads. Cooling Water Passages are Lined with Brass to Prevent Corrosion. Carb Pads Accept Q-Jet or Square-Bore Marine Carburetors

www.compcams.com

This getting old thing, I'll be damned if my brain doesn't get lost sometimes.



I'd love to find these $1k L31s. Yards around here want $2500 for a running one with compression over 150.

I already posted them, not hard to find $300 junkyard l31's or rebuilt for sub $2k.

 

[Chevy_man]

I already posted them, not hard to find $300 junkyard l31's or rebuilt for sub $2k.

When I look on car-part all I find are the $2500 ones with 200k miles.

Guess that's the downfall to people wearing out their junk rather than the suspension rusting off the frame in 5 years.

 

[KacksterK5]

Any Vortec short block will have the same bottom end. Stab a marine roller cam in it, some fresh lifters and summit roller rockers and call it a day. I ran a raw water cooled volvo Penta for 800 hours in salt water, no issues with corrosion in jackets, that I know of. Just flushed it a lot.

 

[RSWORDS]

Brass freeze plugs and send it.

Blue print engines if you want a short block.

Mercury reman if you want a drop in and go with warranty. Literally fuel and battery and it will start.