Polishing Aluminum

[Detroit Bill]

I got this idea that I wanted to polish some Blue Thunder Competition valve covers. I think my goal was to have a project and make some relatively unique valve covers. I bought a polishing kit from Caswell which came with 8" wheels and the different compounds you would need. It was around $100. Thankfully I have a 1-1/2 hp motor with an extended shaft that is perfect for this.

Never having polished anything before I thought I would dip my toe in the water. I bought a Shelby "billet" alternator bracket set. A side note on the Shelby billet bracket, it appeared to be cut on a water jet and moved as it was being cut so the edges were jagged in some places. It was bead blasted over this uneven area. This was actually a good thing in this case because it caused me to have to sand those areas smooth before I started polishing. That gave me experience with what grit to sand to. The answer to the question what grit should I sand to is, as high as you can. Sanding is easier than polishing.

So I polished up my brackets. Didn't finish I need to pick up some finer paper for my DA. 180 is not enough in my opinion. They are coming out good and will be good when I am done BUT I am not feeling the valve covers for two reasons. 1.) It is a dirty finicky job. 2.) And more importantly, Aluminum is soft and I think they would get easily scratched and become a difficult maintenance item. Polishing a new valve cover is not a big thing, a used one would be more difficult cleaning the inside to start and them cleaning it again before you put it back on the car.

So I thought I would share my experience. I would not discourage you from doing it I would just pick my places very carefully. I'll post some photos before I am done.