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Old 10-21-2002, 05:27 AM
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Question 454 Chevy/Mercruiser Big Blocks

Need some direction.

I have a pair of 454ci Chevy/Mercruiser Magnums (365HP), came out of a 34' Wellcraft Scarab. I recently put them up for sale locally in a newspaper and got a lot of calls for them but someone told me to advertise in the auto section because they're worth more.

My question is, what are the downsides of using a marinized big block in an auto or truck, and what are the differences (if any) beyond marine gaskets and brass freeze plugs?
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Old 10-21-2002, 02:56 PM
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the only difference that i know of is that marine application use a roller type of bottom end bearing. the only reason why that i can think of for this is that there is more moisture in the marine application. and yes they work just as well on the street, you just can't rev the hell out of them.i think this is because of the bearings. i hope this helps. <img src="graemlins/pimp.gif" border="0" alt="[pimp]" />
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Old 10-21-2002, 05:39 PM
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generally speaking the only difference between marine and auto engines is the marine engines usually use different head gaskets(stainless fire ring) sometimes the paper is different,brass freeze plugs, and a cam with lots of low and midrange power, but the bearings are all automotive, the rpm limit is not really the engines fault it comes from the prop cavitation problem at over 4500 rpm. externally the bolt on goodies can usually be exchanged for automotive stuff, i have built many marine 4-cyl to big blocks. there really isn't that much difference. now if the two engines were a pair in a boat one will rotate backwards, this is done with special cam and a 2 gear gear drive,if your buyer puts that one in as purchased he may have some problems.
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Old 10-22-2002, 06:33 AM
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the difference is that a marine engine is put together with the best parts like crank and rods. i have not heared of rollerbarings in the crank just cam and you can use a marine block in a truck or car just fine. the gaskets are the same it is the carb and alternator that are the special parts for marine engines. the cam profile might be diffrent, but that is it and yes they are worth a lot of money. the engine in the z06 corvette are made at mercruiser.
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Old 10-22-2002, 01:49 PM
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the only big problem is that, like mentioned above, one engine will rotate the wrong way for automotive use. other than that there is no difference between a GM performanceparts 454 and a mercruicer 454, except the head gaskets and different colour paint. but i dont think you would get mor ethat a couple of grands three max... for an ex-marine longblock engine as the buyer would have to rebuild the engine, or atleast add new cam and so on if he wanted to chance it

sell it to a marine buff, they burn money like there was no tomorrow, try the classifieds at www.offshoreracing.com or somthing loke that,

now if it came with an Arneson ASD-8, a twin disc transmission, a 7 bladed stainless Rolla leaver prop and a gale banks twin turbo kit, i would put it in my 18 foot ski boat... :-)
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Old 11-07-2002, 09:55 AM
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Thanks for the input and replies. Back from my trip. Here's more details on these motors, they are Gen IV's.
  • Hydraulic lifters
  • Bore 4.25
  • Compression 8.5:1
  • Heads - Cast Iron, Rectangular Port
  • Intake - Aluminum Hi-Rise
  • Pistons - Forged Aluminum
  • Crankshaft - Forged Steel
  • Oil Pan - 8 Quarts
  • Heavy Duty Valves
  • Crankshaft rated HP - 365HP each

Pulled from my 34' Scarab, they have approximately 546 hours of use on them, brackish water, very little if any corrosion because of weekly flushing with freshwater. Very clean engines, babied since day one with oil and filter changes every 30 hours.

Have decided to repower and upgrade to 502's after experiencing a blown head gasket in one of them. I was thinking about putting them up for sale $1500/$1200 I'll try the marine guys first and see if anyone is interested.

I was told the counterrotation issue on my Gen IV's might not necessarily apply because Merc made the transition in the outdrives (Bravo 1's), which I have installed. I do have counter rotating props, but apparently the motors may both be the same rotation. That's something I'll have to look into some more.

Thanks again.
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Old 02-08-2003, 07:28 PM
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Can anyone recommend auto and truck sites where I should list these engines for sale? Thanks in advance.
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Old 06-08-2011, 12:27 AM
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Hello, do you still have these? *************

Hello, If you still have one or both please contact me at ********************
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Quote:
Originally Posted by Scarab
Need some direction.

I have a pair of 454ci Chevy/Mercruiser Magnums (365HP), came out of a 34' Wellcraft Scarab. I recently put them up for sale locally in a newspaper and got a lot of calls for them but someone told me to advertise in the auto section because they're worth more.

My question is, what are the downsides of using a marinized big block in an auto or truck, and what are the differences (if any) beyond marine gaskets and brass freeze plugs?

Last edited by 68NovaSS; 06-08-2011 at 07:40 AM. Reason: Classified ad. Please use the Hotrodders Classifieds for classified ads.
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Old 06-08-2011, 07:41 AM
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Please use the free classifieds, and read the board guidelines.

You realize the original thread is nine years old????
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