valve covers

[cokefirst]

I would like the instructions on how to polish these.  I tried a buffer and some jeweler's rouge, but no appreciable improvement. 

[Tom S]

I would not put any coating on polished aluminum parts. If at some point the polishing needed a little touch up you would have to somehow remove the coating even if you only wanted or needed to hand polish a small area or to machine polish out some scratches. There are some motorcycles that come from the factory with  polished aluminum engine case parts. They are not coated with anything & do just fine. I never put any type of coating on the many aluminum parts that I machine polished.
I have to admit that after we lost the only chrome plating shop up here I did spray a couple steel parts for my Roadster that I'd machine sanded & polished to a mirror finish with some clear paint. That car isn't subjected to much wet weather & those parts, one spindle & the drag link still look like they have been chromed. 

[Tom S]

I would like the instructions on how to polish these.  I tried a buffer and some jeweler's rouge, but no appreciable improvement. 

These what?

[cokefirst]

Sorry, I was asking about polishing the Thunderbird aluminum valve covers that came with the engine dress up kit on the 1955-1957 Thunderbird Y block engines.  Thanks

[Tom S]

This pic is probably what I copied off the little package of polishing compounds that I bought from Sears years ago.
Some basic stuff: For aluminum the Brown Tripoli usually does the trick.  While working from coarse to fine with whatever sandpaper or polishing compound you need to sand or polish in a straight line & then go with the next finest paper or compound at a 90 degrees from the last step. I don't think that would work if you are trying to polish with a buffer that rotates. Got to keep the alternate directions in a straight line. On something like the valve covers or anything that has a dominant length you want to finish by going length-ways. <------- -------->
That doesn't work for round parts like a rod or tube. I usually find a way to spin them, polish away & it works just fine.
I made the machine that I use for sanding & polishing. I uses a round expander wheel that I got from Eastwood years ago & long sandpaper belts instead of the little sandpaper belts that come with & just fit around that 6 inch or so diameter wheel & wear out pretty fast. I think the belts I use have a six foot circumstance. I can change them in just seconds. I can also quickly attach different buffing wheels that each are covered with their own particular buffing compound. You don't want to use more than one compound on the same buffing wheel.
If anyone is interested I *might* have some pix of my crude looking sanding/polishing machine on my embarrassingly messy & cluttered bench.