+1 for soda blasting. I use it to clean things I don't want to get glass beads into, like cylinder heads, cases, carbs, etc. It's very good at cleaning the carbon off combustion chambers, ports, pistons, and so forth, and it cleans up with simple water rinsing. It is a bit messy, however, so I use a blasting hood and coveralls. It seems to get everywhere, so I still end up having to shower afterwards.
It's not as aggressive as sand or glass beads, or other blasting media, and I still use them for removing paint, heavy corrosion, and such.
I uses a Harbor Freight soda blaster, and buy the soda in large bags, also from Harbor Freight. I recommend the largest blaster they sell, mostly because you don't have to stop and refill it so often.
Ken