What's the best way to clean and polish aluminum valve covers, especially in the groves? I did a search, but didn't find anything on it. Thanks, Charlie

I will soon be doing mine on my bench grinder with a buffing wheel and compound. The last time I did it was 25 years ago and they came out OK. If they don't come out better than OK this time, I'm going to find a shop that'll do a great job.
Oh, the groves are a great place to color match body-paint or engine paint. Spray where you want color, then wipe the tops of the fins (or what-ever) with a towel wet with thinner. I use lacquer thinner. Works fair;
http://epitomesrebuild.com/images/138.JPG

I did my old M/T's as Fred described, they looked really good, and stay shiny a long time. Used Chevy orange in the fins.

Some sandpaper will go a long way to getting the heavy crud off and getting them ready for polish. When I did my (30 year old heavily oxidized) valve covers, I started at 320, and worked thru 400, 600, 1000, and finally 2000, all done wet. After all that, the buffer brought em to gless in moments.

Depends on whether you want them too look original or real shiny.

For a high shine polish (which is what I think youre asking), the wetsand/buff method works great. The fins can be tedious, but not overly difficult. Just use aluminum polish and wedge some fine steel wool in the fins and work it back and forth.

When polishing Al on a buff...unlike other metals, it relise on heat on the top molecular layers..what in efect happens is the top molrcules are melted and desposited in the scratches
Use a little kerosene.
If u pre heat with an LPG torch, wear leather gloves then start at 1 end and slowly work to the other...dont do big areas at a time.
I use a Stainless steel polishing rouge.Buff wheels com in diff diameters and widths, narrow ones do the groves well
Personall I like the painted groves, also gives better heat exchange
Polish the whole cover, lightly sand the groves, paint the whole top, then sand most of the paint off the ribs but dont go thru the paint..just till thin
Then buff the rest of the paint off.
Polished Al is very prone to corrosion in acid conditions...
If u coat with a clear, and the clear is too thick it will yellow...If it is just misted on, enough to just cover/protect and no more, the thin coat will yello but not enough to notice.

If you want to clean up a a set of Z valve covers I have used a product called evaporust available at autozone...

I do exactly what JimM recommended and my covers that I polish come out great!

Wet sanding up even past 2000 grit up to 2500 or 3000 grit will produce tremendous results.

Okay, I tried to short cut this and got disapointing results---- what a suprise! I have small block Aluminum Z (fined) valve covers. When I started out, they were dirty, half dull and half shinny. I did a 600 wet sand followed by attempting to apply polishing compound (stick paste) using a buffing wheel mounted on a drill. Now, I have clean valve covers, but they are more on the dull side. How can I fix this to make them shinney? Thanks, Charlie

ps: it seamed like very little of the polishing compound actually made it onto the buffing wheel and valve covers. I messed up. Lack of heat??

you can't shortcut. The 600 cuts the crud fast, but the scratches it leaves are too coarse to polish out.

Get some 800, and some 1000, and 2000, and...

Each time, sand until you can no longer see any marks from the previous grit. Any "skipped spots" will be dull in the finished product. They will almost look like a mirrir after the 2000, and will polish to glass in seconds.

Like Jim said, 600 wont polish out as well. I havent done a set to full polish in a while, but I believe I started with a scotch pad to clean, then went 1000-1200-1500 wet, then full polish.

Also, Im not sure if a drill will give enough rpms to get the best results.

This is the last set I went with the full polish on. Yes, Jim...that is/was Bertha :D

http://i20.photobucket.com/albums/b217/RamAirDave/73ZEngine1.jpg

She looks a lot prettier there than here, Dave!
http://home.comcast.net/~Jimragtop2/bertha1.jpg

See this manifold?
http://www.kakariki.net/bradford/newengine1.jpg
That sat out in a paddock for 50yrs...it was so corroded I have to clean up start with a 4" grinder with a 80 grit sanding disk!!
That is 3 1/2 hrs work...still needs a final polish.
After the 4" I used a couple of medium 3m paint stripping disks
Then with an orbital sander with 320 grit wet and dry using kero
4 sheets, dont mess around trying to get the most out of a sheet.
Then 600 in the orbital again.
Hand rubbed out a few swirls...once one gets the 'knack' one doesnt get many.
Then a 8" x 1" cloth buff, in Drill (cause it will not fit on my bench grinder) damped with kero and a stick of Stainless steel polishing rouge..The stuff the pro polishers use!!! not the stuff 'of the shelf'
heated it up and loaded the drill
Close up it needs another 1/2...
Yeah well why didnt I finish it?
Because that engine is going to die and nearly got a another ready to go in.
So may as well leave the final poilsh till then...I would have done one anyway if If it was finished.
From memory there is a similar thread where Jim and I mention about polishing an alternator...We do it slightly different but the basic principles are the same