I have my old motor sitting in my garage and have decided to freshen it up a bit. I've gotten the valve covers and intake manifold off and I noticed that the passenger side rockers are all oily clean (the oil has burned nicely over time). On the driver side though the rockers are all covered in a scaly flaky oil residue (or carbon like). It's not wet oil but burnt looking and easily flakes off when you scrape it. Why is this like that? What could be the cause of this?

 

Using crappy dinosaur oil.

As for why one rocker set was nastier than the other, no clue.

 

Could be the fresh air from the PCV.

 

The stock water pump flows better into the passenger side. Cylinders 1-3-5-7 run hotter than 2-4-6-8. Or so I'm told.