You can use Eagle One Etching Mag Cleaner, or just cast aluminum cleaner. It will turn them both white in color. I always used this stuff on my aluminum heads/block.. and they always look near new after.... Just use brush and scrub them soaked in this stuff.
[color:"red"]65 Hemi Belvedere coming soon [/color] [color:"#00FF00"]557" Indy engine 1.07 60ft 144mph in the 8th 2100 lbs package [/color]
