Cleaning Aluminum Valve Covers

There's quite a few threads about blasting medias (use the Search key) but here's a fairly recent one with some good suggestions.

http://www.forabodiesonly.com/mopar/showthread.php?t=161490&highlight=blast+media

Personally, I use Black Beauty (coal slag) ... if you have a Tractor Supply store near you, you can snag it in 50 pound bags for about $15 or so. It lasts a lot longer than blasting sand, cuts better and won't hurt your metal if you pay attention to what you're doing.