Time Frame for Manifold replacement? Source?

My Trojan F26 has a 1968? crusader 454 of unknown vintage (on the rebuild). I believe it was rebuilt and installed between 2006 to 2008. I have not put a great deal of hours on it, running in mostly salt water. I do however, flush it thoroughly with fresh water after each use using the the garden hose attachment that is plumbed into the sea strainer.

I need to know how long can I safely go before needing to replace my manifolds and risers and what is the best source for getting them. Oh, and does flushing the engine extend the life of the manifolds?

Thanks for any help. Roy

While I know of boats that have been in the brackish waters of the Chesapeake for thirty years with the same manifolds, that doesn't mean that you should let yours go that long.
The only way to know is to look inside. Take the riser off the manifold and check out how rusted they are. If they are packed with gunk then you'll certainly want new ones.
Crusader manifolds are quite dear. I'd be caught derusting them and trying to squeeze another season or two out of them.
Remember the cast iron on the Titannic is still in pretty good shape even tho it has been in salt water for 100 years.

Trojan Man said:

My Trojan F26 has a 1968? crusader 454 of unknown vintage (on the rebuild).

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Do you have heat exchangers?

I am sorry, it is a raw water cooled engine.

I don't have personal history with salty manifolds. The risers/elbows are a 4 year item, even with flushing. Since the manifolds likely stay filled with water, they may go a bit longer, but mistakes here will be costly.