Best way to clean cylinder heads?

Whats the best way to clean cylinder heads.. the valve covers are off and everything, so whats the best way to clean them without damage the valve or ports or anything?
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What part of the head are you trying to clean?

 

are the heads off the motor and how nasty are they?

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The heads are off the motor and I just want to clean everything. They got kind of dirty from sitting around for just a few days. They're getting a valve job and some machine work so I just want them to be a little cleaner before I send them off.
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Let the machine shop vat them after he takes them apart. That'll clean 'em real good.

 

Part of the valve job should be cleaning the heads in a tank or pressure blasting cabinet

 

I used deisel fuel to clean things up. It's cheapper than cleaners & that way I didn't scrimp on how much I used. But if you're taking it to a shop let them clean it up (That's their Job). Good Luck!

 

Oh alright haha thanks guys. I'll let them do all the dirty work
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buy new ones

 

I'd let them do the grunge work...they will anyway. But for future reference, I've used oven cleaner very successfully on heads that I've rebuilt at home.