I just received some heads for our 3.4 build and I'm surprised at some of the excessive carbon build on the combustion chambers. I have included pics below.
Here are the specs:
3.4 JE Pistons 10.5:1 compression
Twin Spark Andial Splitter
20/21 cams
Wong Chip
These are 15K heads and the carbon is thick!
I'm loosening the carbon with a simple green soak and it really works!! Softens the carbon so it can be scraped from the chamber. The heads were fully rebuilt 15K ago by Ollie's but I guess there could be a bad valve stem seal. I have NOT run these parts but just bought them and beginning to clean them up.