What are Valves made of and can I clean them?
 

I have R56 valves out and before I replace and lap them, I wanted to know what they are made of? I wonder if I can clean them with a wire wheel. I have the soaking in gasoline right now, but it would speed things up if I can wire them.

I did mine, and it seemed to work fine. Valve are hardened steel and should hold up to a wire wheel fine. The best results I had was taking them to the machine shop and they "tumbled them" and they were nice and shiny from the severe oil fuel gook that coated them.

Any problems with letting them soak in gasoline to soften the carbon?

Serious fire hazard to use gasoline for parts cleaning.

I prefer when ever possible to avoid using anything that might scratch something like a valve. Any surface damage could turn into a stress point and lead to failure.

For cleaning things like valves I had a can of carb cleaner -- can about the size of a gallon paint can -- which had a metal basket I could lay parts in the basket -- being careful the valve heads don't mar the valve stems of other valves -- and then put the basket in the cleaner -- submerge it -- and then put the lid on and let the parts soak for a day or two. For alum/mag. metal part read the instructions. While the stuff was for cleaning carbs -- alum. of course -- it was rather caustic stuff.

After a proper soaking then I could use a parts cleaning brush and some non flammable parts cleaner and remove any residue on the metal parts.

Be sure afterwards you dry the valves thoroughly and coat them with engine oil to avoid any rust spots forming.

Just before head assembly spray each valve with aerosol electronics cleaner -- residue free cleaner -- then oil again with fresh/clean engine oil and install in the engine.