I'm in the middle of rebuilding my 100k mile B18c, i'm now getting to sorting the head out and when i've pulled the valves out i've been greeted by this mess.

The intake ports and seats are fine, a little lapping will bring them up.The exhaust ones, however, are pretty messed up. As you can see the seats have really heavy carbon buildup around them and the ports are coated thick in it too. The motor was using a lot of oil previous to me stripping it, could that be the cause of this? What do I do to get it cleaned up? I've ordered some supertech valves/springs/retainers too.

Ohh the car runs an Apexi PowerFC on a map by a reputable tuner over here in England, 4-1 and Buddy Club Pro Spec exhaust.

 

Not sure what caused it...burnt oil could be the culprit. Too clean it up I would have the head cleaned up and machined at a local engine builder/machine shop. Have them do a 3 angle valve job and you should be good to go! They will be able to tell if there is any valve seat damage other than carbon build up.

 

That's what my head looked like after 30k boosted miles. It took me a week to scrape and clean all the carbon off. I lapped them in just fine.