U20 Valve Cover Finish

[theunz]

What are you guys doing to refinish your U20 valve cover. I put a black wrinkle finish on mine years ago, but would like to change to something closer to OEM. It seems to me that originally it had a somewhat shiny natural aluminum finish. Cleaning won’t achieve that. I’ve tried bead blasting, and while it looks much better it leaves it with a satin finish. I’ve got a spare that I bead blasted but it still has a stained appearance on the sides. It looks like about every 2 inches it changes from clean to stained. I polished one side and it made the staining much less noticeable, but now all the tiny stress cracks show up like a sore thumb. I suppose a professional polish where you spent hours progressively using finer and finer sandpaper would do the job, but a mirror finish is not my objective. Neither is hours of hard labor. Today I bead blasted it again and painted it with some aluminum engine paint, but still not what I’m after. Tomorrow I might try some cast aluminum paint and see what that does. The only other option I can think of is to find someone with a large ceramic stone tumbler. Anyone have good results achieving a factory look finish?

[bakerjf]

I had mine vapor blasted to achieve something of a uniform finish and then brought it to a restoration shop that had a dumpster-sized tumbler (it was not anything like a stone medium). It spent a weekend in the tumbler.

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[C.Costine]

Powder coat. I haven't had the valve cover done yet but I am going to. I had the intake manifold done four years ago and it still looks like new aluminum. It eliminates any possibility of oxidation.

[spl310]

They were just a natural cast finish. The tumbling that John had done is probably closest to OEM.

[theunz]

Tumbling is what I figured was the factory finish. Now I wonder if after 50+ years the result would be the same? The bead blasting hides all the tiny stress cracks, but will tumbling allow them to show again?