How can I clean the exhaust manifold?

[sookati]

Hey Everyone,

I have an SBT motor coming in, and when I pulled off the exhaust manifold, the channels for the water need to be cleaned. There's just a bunch of deposits in there. How can I clean it? Can I leave it in a bucket of CLR overnight? I just want to put good stuff back on the new motor and don't want to start with cruddy bits. Let me know what's worked for you.

Thanks!