Mercruiser SS riser...point me in the right direction.
04-21-2014, 05:24 PM
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Mercruiser SS riser...point me in the right direction.
Just bought a 22 eliminator extreme with a 454 that was hydro locked from what looked like a shredded impeller and overheat. Motor is almost of of the shop. Full rebuild. My question is I am going to replace the manifolds because they are original and have rust In The exhaust chamber. The risers are oem mercruiser stainless steel. Looks like they are in perfect shape. Only rust wast tiny on mating surface where water might have got passed the gasket at one time. So should I buy the new manifolds and reuse the stainless steel riser. If I check the gaskets and torque yearly is it safe to use the ss riser? Thank you. Btw this boat is primarily fresh water use. Maybe 4 salt trips a year. 
04-21-2014, 07:11 PM
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There is a problem with those particular risers. They tend to allow water to leak past the gaskets. Seems to have something to do with having cast iron manifolds and stainless risers. Maybe the different metals expand and contract at different rates when heat cycled.
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04-22-2014, 02:08 AM
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Buy a set of used 496 manifolds. If you can find a set of freshwater alum 496 manifolds then thats even better. They are dry joint.
Chris
Chris
04-22-2014, 02:25 PM
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I didn't think that the 496 manifold was compatible with the 454. Of course I'd want a dry joint system but I have heard there is not a conversion available. I also have thru hull exhaust so not sure if that would affect to swap.
04-22-2014, 02:41 PM
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The 496 manifolds will fit on a 454.. You man have to make a couple brackets and such but it would be worthwhile. The don't make dry joint manifolds like for the small blocks that fit the big blocks as those don't cool as well as the old style. Not going to debate the cooling thing but its just the way it is. Not suitable for big block. The 496 version will cool it just fine and probably pick up a few ponies.
Chris
Chris
