motor swap

[dj huffman]

I recently wasted the motor in my boat. It's a 96 scarab22 with the 330 mag. 454. I'm wanting to put in a 502. I see the 502/502 motors advertised from gm as crate motors. Can I use one of these, I guess what I'm asking is, is there a difference between marine motors and these crate long blocks.

[BOFH]

Yes. Primarily the freeze plugs and head gaskett. A "converted" engine involves replaceing the freeze plugs, a marine head gasket, and any other goodies needed for the accessory drive system.

[Dave F]

Ya, as has been said just make sure that it has brass freeze plugs, which I think it does, and use a Fel Pro 1047 head gasket.
Careful with the 502/502 cam. It can cause reversion in a stock Merc exhaust system. You can use it but there are other cams that are better.
DAVE

[502procharger]

my buddie did the switch in his eliminator. he actualy left the stoch head gasket, but should have changed it. has had no problems. his boat gained like 12mph and a ton of acceleration. good luck with the swap. dave f is right(reversion) now might be the time to look into some headers so you do not worrie about reversion. it is a shame to pull a bran new cam and such, put the money towards some good aftermarket exhaust that will work well with the stock cam and give you some hp to boot.

[Dave F]

Well, if reversion is going to be a problem because of current exhaust, it would depend on how much money you had to spend.
If your gonna have or already have real good exhaust you don't really want the cam it comes with anyway. Like I said however, You can use it if you want. It's just not optimal for a boat.
If you don't have good exhaust, we can run some numbers for a cam to give you optimum performance with what you have.
That way the only thing you need to spend additionally is around $250 for the cam instead of $250 plus whatever your exhaust will cost.
What you'll have to accept is you'll be in the 415-450 hp range instead of 500 depending on compression ratio.
DAVE

[dj huffman]

Thanks to everyone who answered my questions. It's been a great help. I'm running stock exhaust manifolds right now, but would like to switch to headers during the change. The compression ratio is 9.6 to 1, and the camshaft is 0.527"/0.544" hydraulic. Should I change the cam, and if so, does anyone know what to. Again, thanks for the help.

[dj huffman]

Thanks to everyone who answered my questions. It's been a great help. I'm running stock exhaust manifolds right now, but would like to switch to headers during the change. The compression ratio is 9.6 to 1, and the camshaft is 0.527"/0.544" hydraulic. Should I change the cam, and if so, does anyone know what to. Again, thanks for the help.

[Dave F]

Ok. So you're going with the whole engine?
The 290cc large oval port aluminum heads, and chevy aluminum intake etc.?
I've never heard anyone say how much work you can do to those heads.
Do you want to stay with stock springs? That will be a big factor as well.
DAVE

[BOFH]

Especially with Aluminum heads, you want a closed cooling system. I actually like them with any engine that is important to me.

[dj huffman]

Dave F:
Ok. So you're going with the whole engine?
The 290cc large oval port aluminum heads, and chevy aluminum intake etc.?
I've never heard anyone say how much work you can do to those heads.
Do you want to stay with stock springs? That will be a big factor as well.
DAVE

[dj huffman]

dj huffman:
Dave F:
Ok. So you're going with the whole engine?
The 290cc large oval port aluminum heads, and chevy aluminum intake etc.?
I've never heard anyone say how much work you can do to those heads.
Do you want to stay with stock springs? That will be a big factor as well.
DAVEIt's the zz502/502. This is the motor that I'm considering. I can change the head gaskets, brass freeze plugs. I just want to make sure that I can run this engine is a boat. It would be a great gain in hp's. I'm just worried about reversion, and such things. Can I run it cooling it with raw water? Any information you could give would be very helpful. Thanks again..

[dj huffman]

dj huffman:
Dave F:
Ok. So you're going with the whole engine?
The 290cc large oval port aluminum heads, and chevy aluminum intake etc.?
I've never heard anyone say how much work you can do to those heads.
Do you want to stay with stock springs? That will be a big factor as well.
DAVEIt's the zz502/502. This is the motor that I'm considering. I can change the head gaskets, brass freeze plugs. I just want to make sure that I can run this engine is a boat. It would be a great gain in hp's. I'm just worried about reversion, and such things. Can I run it cooling it with raw water? Any information you could give would be very helpful. Thanks again..

[Dennis Moore]

You can build a little bit better marine engine than the 502/502 using almost identical parts. The 502/502 is built using the 502 HO partial engine assembly and the high performance ZZ camshaft. Added to it are the 290 cc intake port, 110 cc combustion chamber GM Signature Aluminum heads. The heads are actually made for GM by Edelbrock. The oval port intake manifold is also made for GM by Edelbrock.
Buy the 502 partial engine (by the way it does come with brass freeze plugs). Buy the 502/502 ZZ camshaft and single row timing chain and sprockets. Next purchase Edelbrocks hard anodized marine aluminum cylinder heads #61459, these are the same as the GM Signature heads except that they are hard anodized for corrosion protection and have inconel exhaust valves, purchase the Edelbrock oval port intake manifold. Add a GM marine oil pan, marine water pump, marine carburetor and marine ignition. Buy the rest of the pieces from the 502/502 parts list.
Makes a hell of an engine!
Sincerely
Dennis Moore

[twistedpair]

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