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496 Mag exhaust manifold any way to do FWC

T

tworocks

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"Ok - I have a set of 496 mani

"Ok - I have a set of 496 manifolds and risers. My question is...is there any way to make these fresh water cooled manifolds? It's my understanding that they are raw water cooled, and the Mercruiser 496 Mag system is technically a 1/2 system as far as fresh water cooling is concerned (fresh water cooling to the block only).

Note: these are going on a 454 build as an upgrade (they flow MUCH better than the models of old and have the added benefit of a dry joint at the riser.) I just want to make them FWC, and need to buy the necessary parts."
 
"If I follow all the diagrams

"If I follow all the diagrams for the 496 from that link I get the impression that ALL 496's are 1/2 systems.

Is that correct?

If you read the OP, I don't have a serial number - this is a 454 upgrade."
 
All 496/8.1 engines to date ar

All 496/8.1 engines to date are 1/2 systems. I don't think you can make those manifolds closed cooled. I think this is one reason they stopped using the aluminum manifolds and now use cast iron of a nearly identical design.
 
"Try from here and look for th

"Try from here and look for the 454 model since that is what is on it now. You may need to upgrade heat exchanger to handle the heat load. I saw a new kit that does the block and manifolds at another site. As I understand it, all you need is to put nonvented gasket between the manifold and riser. Then route fresh water to the manifolds and back (you may need a plate w/fresh water outlet)to the exchanger. The hot raw water from the exchanger that went to the mans. now goes to the risers.

http://www.mercruiserparts.com/SelectModelType3.asp?class_id=1"
 
"OK, so it sounds like I am do

"OK, so it sounds like I am doing something unique and new...I like that.

Guy G. - one nice thing about the 496 manifolds and risers is that they are a dry joint...no need for a special gasket, and as things age and thermal cycle there is no chance of a leak.

This is a ground up build on a 454, so I need to get a heat exchanger anyway. I'll just make sure it's rated for a 'full' system, and run the plumbing accordingly.

One reason I have to do this is I have the older aluminum manifolds (bought used, but they are new take offs) and will be running in salt water. The other reason is that I refuse to run salt through my block.
"
 
"two rocks:

I assume you

"two rocks:

I assume you are running a Bravo drive that will have a raw water pump. You may need to revise the T'stat hsg. I suggest that you use all new water hoses since the system will be pressurized. Post a pic. or 2 when she's done.

Scan thru the site below for the complete kit you need. Pay particular attention to the fan belt configuration; V or serpentine and carb. vs. MPI. I couldn't find one here.


http://bpi.ebasicpower.com/mm5/merchant.mvc?"
 
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