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5.7 King Cobra

fatherof4

New member
Hello, new member here. I have recently purchased a '92 5.7 King Cobra that has a busted block. The outdrive seems to be fine. What should I expect to pay for a remanufactured motor and install? I am a bit confused when I find different placesthat have long blocks for $2000 +/- and then I am told $6000 for a short block by a local repair shop. Any help will be appreciated.
 
busted from freezing?
where the exhaust manifolds destroyed too?

might be best to look for a used, complete OMC dressed motor if so.

Its a fair amount of work to swap a long block into a boat.

a bit of engine assembly knowledge required, good tools, and some special tools like a harmonic balancer puller

You can buy a new Chevrolet "crate" 5.7 for around $2000, but you'll need to swap your engine coupler and flywheel

You can get a rebuilt for around $1500 e.g. Rapido

labour to swap in a long block (either above scenario), probably another $1500 or so

to swap another complete, used 1992 5.7 OMC would be much less labour

that $6000 thing kinda screams "that's not the kind of work we want"
 
yes a 1992 5.7l truck motor will work, got a low milage one? Jut dress it with all the externals off your old motor if they are good, not cracked.

If man's are cracked i would buy a 500 dollar kit that has 2 man's 2 risers, and all the gaskets in one nice box.

That way your good to go for at least 5 years.

Junkyards are full of 5.7's they were supposed to destroy them bull.

So under a grand you should be ok my way. Your labor. Mechanic who knows.

Got a strong tree with a chain hoist, do it yourself. I did.
 
There is very little difference between a truck engine and a marine engine. Marine engine will have a slightly different cam, 4 bolt main bearing caps, double valve springs and brass casting plugs. A car version of a 350 has too many variations. Get a Blazer or Suburban or pickup engine.
 
I could not recommend a car/truck engine to you!
I would suggest that you match year model as to avoid flywheel and "tin wear" conflicts! (although this would be pre '87)

If raw water cooled (and my guess is yes on that) you will want the marine head gaskets (auto/truck will not have this).
You will also want the marine profile camshaft.
As for the other required parts ..... I'm sure you know the importance of them!

If this is for a small hull, and if Closed System cooled, you may squeak by with an auto enigne..... Again, I can't recommend this.

.
 
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I have a 92 454 King Cobra freeze and crack the "windows" in the block. I found a deal, had a complete rebuilt long block for $1400 and install was $900. Runs great!

Problem is now it leaks water into the hull. Motoring around for an hour there will be a couple of inches, bilge pump takes care of it no problem. But left in water overnight it will fill it to the level of the floor.

Can this be caused by the freezing? Something in the out drive?
 
So the water is leaking in all the time, not just when the engine is running, is that correct? Could be a bad drive shaft bellows or shift cable boot. Do you leave it with the drive up or down?
 
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