Stick with low heat. The test engine I cooked on 'high" came out clean but lost the shine on all the external aluminum parts. Its some sort of deposit that doesn't come off.

Another tip: remove plastic bits bfore cooking the engine! When heated some types of plastic release (something nasty) which coats everything in the pot. Plastic throttle arms are the main culprits here.

Other than those two gotchas the procedure is quite simple. Fill the pot with antifreeze, set to low heat, drop in the engine parts. Come back in a 10+ hours, remove the parts. Flush out the remaining antifreeze with water, oil, assemble and run briefly. Done!