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i bought a 85 silverado swb about 7 years ago ...im just now getting around to a frame off resto ....when i bought this truck the guy told me that the motor came out of a boat and its a high rpm motor ...that kinda went in one ear and out the other ...lol well now that im starting the motor build i looked up the numbers on the block and it lead me straight to ......5.7 Litre (350 CID) New Marine Engine
275 hp @ 4800 RPM / 340 lb-ft @ 3200 RPM (4bbl)

Replaces 1986 thru 1997

1 Piece Seal, Roller Cam, 4 Bolt Main, w /Mechanical fuel pump pad.

Comes with Cast Iron Intake Manifold that excepts either type of 4bbl Carb, Marine Water pump, Balancer, and Flywheel.

(12 bolt pattern style for your Intake Manifold) Now my question is is this motor worth building ...with the heads and internal parts i have im trying to reach 450-500hp is this block worthy of that or should i start looking for something else to build .....i took this truck to the track one time and with out knowing anything about the motor or what it has in it i ran 9 flat in the 1/8 mile witch is not the fastest in the world but i didnt think it was half bad considering my friend was in his trans am ram air factory 345hp and it was running the exact same time of 9 flat ...since then the truck has been parked and only started every few months... any help will help i dont wanna spend time and money on this block if its not going to perform or last
:welcome: :confused:
 

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Check the block casting. After about 1976, street castings were used in boats, so whatever the casting number says, that's what you have.

If its a roller from the TBI days, I would say yes. If its a Vortec-era block, its still fine but not quite as beefy as the older blocks. Heads are probably old-school smoggers and would require lots of work, but if you're looking for 500 hp you'll need to do work to the heads anyway (or get aftermarket)

After about 1985, its very difficult to tell a marine engine from a street assembly. Even cams were remarkably similar. The roller cam in my 5.7 Vortec in my boat is a Mercruiser spec and its 196/206 with a 112 LSA. I'd run that on the street any day.
 

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curtis73 said:
Check the block casting. After about 1976, street castings were used in boats, so whatever the casting number says, that's what you have.

If its a roller from the TBI days, I would say yes. If its a Vortec-era block, its still fine but not quite as beefy as the older blocks. Heads are probably old-school smoggers and would require lots of work, but if you're looking for 500 hp you'll need to do work to the heads anyway (or get aftermarket)

After about 1985, its very difficult to tell a marine engine from a street assembly. Even cams were remarkably similar. The roller cam in my 5.7 Vortec in my boat is a Mercruiser spec and its 196/206 with a 112 LSA. I'd run that on the street any day.
Ayuh,.... Mercruiser, has been usin' basic pickup truck long block motors from Chevy, since the beginnin'...
And still does...
Unless yer talkin' Hot Rod, Go-fast boats, yer talkin' standard production pickup motors...

Like Curtis says, the castin' numbers tells ya what you've got...
 
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