cleaning up the slant six head

Intake is cast iron, I dont think I would venture soaking aluminum in Vinegar at this point, I may be mistaken but I believe I have read that it will eat it up pretty quickly.

I tried removing the pot metal vacuum nipple from intake before I set it in there, it broke off down below the surface of the intake, I am hoping that the vinegar will just eat what left so I do not have to mess with trying to get it out.

Have you had any experience with soaking aluminum parts in the Vinegar solution?