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Help verify engine please

boatingfun1

Contributing Member
Hello im new to this forum. Need help with finding out what motor i have. I got a boat for free and need some help.

I know the block say's 5.7l engine block number 10243880. I found numbers on engine EC021154, and 2m04253mn.

Thank you
 
79d09685-6a55-48e1-be59-f6bacb7979e2
 
If it has not been bored first over, that would be a GM SBC 5.7L engine fitted with the dreaded GM Full Dished pistons!

It is also set up with a roller cam follower camshaft.

With the long body coolant circulating pump, it's most likely an Automotive SBC.

What are your plans for it?
Are you thinking about using it in a Marine application?


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Boat.jpgI was told it came out of Master craft ski boat. 1998-02. Has indmar intake, Brass freeze plugs. Going in this boat.
 
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View attachment 25358I was told it came out of Master craft ski boat. 1998-02. Has indmar intake, Brass freeze plugs. Going in this boat.

I’m sorry, I don’t think I can help. I would call Mastercraft to see if they ever used a GM engine, I doubt they would but who knows. I also thought it looks automotive, though Mastercraft would normally would have an inboard. Sorry to be of no help.
 
We typically do not see the long body engine coolant circulating pump being used in a Marine application.
This is what leads me to think that the engine is an automotive SBC.
If so, it will not be correct for your use without some internal changes.


Here are a few SBCs used by Mastercraft in/around 1998.
As you can see, they are using the short body Engine Coolant Circulating Pump.


(one pic deleted.... too large)


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The rest of the motor parts look just like the motor you show. The motor does have brass freeze plugs. Anything else i can show on the engine to help? Also has marine heads, per the part number i looked up.
 
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.........
The rest of the Engine parts look just like the Engine you show.
Yes, the Marine version SBC engine is based on the Automotive engine.


The engine does have brass freeze plugs.
Those are casting core plugs... aka welch plugs.
"Freeze plug" is a misnomer and is a carry-over from years and years ago.


Anything else i can show on the engine to help?
Not without pulling the camshaft to get the p/n.

Also has marine heads, per the part number i looked up.
Again, the Marine version SBC engine is based on the Automotive engine..... so casting numbers may be the same.
 
Ok cause someone gave me the wrong info on this motor then. They told me it was a indmar. But i looked up the numbers and its not a indmar. But some say Indmar used gm motors. So what do i have to do to use this motor in the boat?
 
it looks like a GM 5.7 vortec...

if it came out of an inboard and the wellcraft has a sterndrive, you'll have to get the mounts to match and a coupler...probably some other bolt-ons as well...

I'd just measure the cam to see what it is...unless you are tearing the engine down to rebuild it...
 
Mark said:
I'd just measure the cam to see what it is...
I agree with Mark.... use a dial indicator and degree wheel, and lean the camshaft specs. The over-lap needs to be suitable for Marine use.

unless you are tearing the engine down to rebuild it...
Looks as though he's doing a re-furbish, not a true tear-down and rebuild!


Are you planning to leave the crankshaft and camshaft installed while you do this work?
If so, make sure to cover the connecting rod journals prior honing the cylinders.


https://www.youtube.com/watch?v=f7JuMGsyDAg

Are you planning to re-use the GM Full Dished pistons?
If so, check the fit, and make sure that the piston dish volume is correct for the cylinder head combustion chamber volume.
This will determine the Static C/R. It must be suitable for Marine use.

If not, I would suggest using a LCQ style piston that is suitable for your cylinder head combustion chamber volume.

fetch




Since your cross-hatching will be rather light, you may want to consider going back together with cast iron rings.


If this will be raw water cooled, you will want to use the Marine head gaskets.
If it will be closed system cooled, a high grade automotive gasket set will work.

Once the heads are back on, I would suggest using the 8 stop static cam follower adjustment procedure.... not the 2 or 3 stop.

Make dang certain that your ignition system is correct for Marine use!
The automotive system would not only violate USCG regs, the advance curve would be incorrect and could cause damage!


Good luck!



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Thank you. It will be closed it has a fresh water tank to hd the water to keep the boat engine cooled. Will it hurt the engine if i use marine grade Gaskets anyway?
 
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Thank you. It will be closed it has a fresh water tank to hd the water to keep the boat engine cooled.
Although you will see the term used, Fresh Water Cooling is a misnomer. There is nothing fresh about Ethylene Glycol and distilled H2O.
These are Closed Cooling Systems.
What you're calling a "tank" would be the Heat Exchanger.



Will it hurt the engine if i use marine grade Gaskets anyway?
No, but you will unnecessarily pay more for them.
 
What is a good site to order rings and gaskets from?



Most any good auto parts store can get the parts for you.
If you plan to reuse the GM Full Dished pistons, take one in with you so that they can order the correct piston rings.
Make sure that they understand that you have ONLY honed the cylinders.

 
Was wondering if you would know the starter part number for this motor? No tags on the old starter.

The GM SBC used two flywheels..... I.E., a 153 tooth ring gear, and a 168 tooth ring gear.

The 168 uses the starter motor with the staggered bolt pattern.


shopping



The 153 uses the starter motor with the straight across bolt pattern.

shopping


In either event, I would suggest buying a HTGR/PMGR starter motor.


The one that I prefer is what they call the "square block" starter motor.
These use all steel reduction gears (no nylon)
They also work with either the 153 tooth or the 168 tooth flywheel ring gear.

shopping


Which every way you go, be sure to get the correct length mounting bolts with it.
The wrong length bolts will get you into trouble.



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Sorry to bug you again. Do you have a picture of how the wiring harness is routed. been goin crazy looking for one.

thank you
 
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