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Discussion Starter #1
Is there anything special about these blocks?And how big can you safely go biulding one?
 

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They are a heavier casting....but i don't know how far they can go

Maybe check with GM, or someone will chime in

They ARE heavier then car blocks and can go farther....i believe
 

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Discussion Starter #3
I figured they would have to be a beefier casting.I'd like to know how big they can go.If I can get 520 inches plus that would be the shit.
 

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from what I know, most have 2 bolt mains but some of the High-End Performance boats should have 4 bolt blocks.... I know my brothers 30' Velocity did back in 1988 due to a shortage of the standard 2 bolt 454/330HP Mercruiser blocks...the marine engines are beefy but check to sea if the engine was "raw" water cooled or had heat exchangers on it, raw water cooled blocks could be heavely rusted internally vs one which used heat exchangers...
 

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I'm not sure about the 454's, but some of the 502 marine engines used Mark IV Bowtie blocks. Look for a Bowtie cast in the block below the middle freeze plug on the starter side. I have one in my car now, only it's grown out to be a 1100 hp supercharged 540.:cool:
 

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The actual "marine" long block is identical to the passenger car blocks and heads. The only differences are that the engines slated for marine use are "marinized". Stainless waterpump impellers and pump backing plate. Brass core plugs. Stainless t-stats and SAE J1171, ignition proof electrics and fuel systems. The camshafts are also spec'd for RH or LH rotation and high RPM power bands..

Steve
 

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The actual "marine" long block is identical to the passenger car blocks and heads. The only differences are that the engines slated for marine use are "marinized". Stainless waterpump impellers and pump backing plate. Brass core plugs. Stainless t-stats and SAE J1171, ignition proof electrics and fuel systems. The camshafts are also spec'd for RH or LH rotation and high RPM power bands..

Steve
x2
 

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Discussion Starter #8
Thanks guys.Theres one here local for sale and the guy says it can go 540 inches.Just trying to research ot a little before we throw the dough out there.
 

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Thanks guys.Theres one here local for sale and the guy says it can go 540 inches.Just trying to research ot a little before we throw the dough out there.
Always sonic check a used marine engine block. The salt water corrosion,( from the cooling system), to the water jackets is nothing compared to the pollutants that are in the waterways, let alone the electrolosys from the poorly designed electrical systems that boats have. THEY ROT FROM THE INSIDE OUT QUICK. Ground paths and salt water DO NOT MIX.

I've been in the marine industry my whole life. That is why I can comment on this without reservation.

Steve
 

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Thanks for tje heads up man.I dont think this guy knows what he has.He listed it as an 8.1liter.I'm geussing its a late model 8.1 out of a truck.
 

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umm the 454 marine blocks that i have seen have some extra ribbing in the lifter valley area.. thats visually seen and different than regular blocks.. im not sure about other things :ie wall thickness, main web thickness ..etc if there were no difference why would they Cast "marine" in it?
 

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They are ALL GM base engines, when it comes to the 454 or 502). I have 8or 9 in my shop right now and all of them are bow tie with exception of the earlier models that are typical stampings,(HI PERF, PASS etc). Who had there label on the one you saw, (Mercruiser, Volvo, etc.)? Just curious.

Buy the way the OP wants to know if he can use a marine block. Lets stay on target with the OP's question so as to not muddy up the thread.:p

Steve
 

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Discussion Starter #13
Thanks Steve for tryin to stay on topic.I just need to know if this block will go over 520 inches like the selling it says it will.
 

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Discussion Starter #15
iRe: 454 marine block?

Thanks jshelton.Thats what I need to know.Is $350 aa good price for the block and it comes with the factory crank,rods,and pistons?
 

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Re: iRe: 454 marine block?

Thanks jshelton.Thats what I need to know.Is $350 aa good price for the block and it comes with the factory crank,rods,and pistons?
JUMP ON IT DUDE! If it passes the test u've got a great foundation for your 540. 850hp on pump gas with no problems. I've got the same block in my 3500lb Chevelle.,runs 10.0'[email protected] shifting at 6400,4.30 rear gear on a 14.5x32 rear tire.this motor will never hurt itself running these rpm's! good luck!
 

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They are ALL GM base engines, when it comes to the 454 or 502). I have 8or 9 in my shop right now and all of them are bow tie with exception of the earlier models that are typical stampings,(HI PERF, PASS etc). Who had there label on the one you saw, (Mercruiser, Volvo, etc.)? Just curious.

Buy the way the OP wants to know if he can use a marine block. Lets stay on target with the OP's question so as to not muddy up the thread.:p

Steve
I also have a 454 marnine block in my garage with the factory forged crank, it is stamped with PASS iirc, but has a Mercruiser tag on the block. I believe the motor was the original in a 1988 or so Cobalt 24ft boat.
 
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