I'm in the middle of an LS1 teardown.
Last weekend I removed the valve covers to and found it hard to see anything, as the pictures below will evidence.
While I wait for an opportunity to resume the teardown this weekend, I wonder what could be responsible for making the insides so black.
I can say that the residue feels hard, scaly and not very oily. There are some puddles of oil around a few of the valves, so I expect some of the valve stem seals to be shot, but would that alone explain the all-round blackness of everything in this valvetrain?