Media tumbling a mag case

[Gary De]

I'm getting ready to send Ollie's a mag 7R case. Is it worth having it tumbled? The alum case pictures show an almost polished finish which looks great. What can I expect tumbling a mag case? Will it turn to a light gray from the almost aged black look?

Thanks guys
Gary

[Walt Fricke]

My understanding is that this is not only not worth it, it is a bad idea for a mag case. The surface oxidation of the mag cases is, I think, even more problematic than it is for aluminum (where it forms a protective coating, doesn't it?). After a while mag cases, or some parts of them, can look as if they had rusted and lost material. Polishing this is just going to accelerate this, I think. And if it changes color with polishing the surface, I believe it will quite quickly revert to what it was.

[AV8TOR]

Greetings Gary,
I am in the pocess of restoring a 914-6 (#2463, a '70). I sent the little 2.0L magnesium case out to George and Ike at Ollie's to have it align bored and new oil pressure relief tap done.
I could not decide If I needed the case tumbled in the media to clean it simply because the
old mag cases just don't clean up like an aluminum case. I went ahead and had them tumble
it ($120) as this car is going to be a "show" car. I got what I expected, nice and clean smooth
surfaces, but not shiny and bright. The magnesium ages and turns darker as heat ages the case. The tumble only makes the finish "clean".
Tom/AV8TOR
Colorado Springs

[The Dude]

Ollie's tumbled my mag case -- no complaints.