How do you clean this s*** of exhaust valves?

I've tried leaving them overnight in carb cleaner and nothing.
Wire wheel also doesn't work.
Only thing that would work that I can think of is putting them into drill
and sanding them, but that would probably damage valves.
Is there any way to clean this without making damage to valves?

 

Usual method is bead-blasting, for ones that are worth the effort.

But for worn-out used-up stock garbage ones like that, this right here is the best way to clean them.

http://store.summitracing.com/partde...AN%2D10577%2D8

 

They're cheap enough to replace, you might as well spring for it. Those don't look horrible, but they're so glazed over with crud that it's going to take a lot of effort to clean up. I mean, how much is your time worth to you?

 

IMO they're HORRIBLE.... seats are DEEPLY pitted, there is the beginning of a missing chunk out of one side of it, and it's STOCK. Heavy, thick, easily warped, soft metal. Not worth spending a dime (or a kuna) on.

 

 

Problem is that this valves are for 2.0 cosworth engine and, accordingto owner, are hard to find and expensive.