I just got a used L98 vette tpi motor and pulled the valve covers and found black plastic crap in the oil return valleys (looks to round at one time) any one know what that could be from? It is a roller cam roller lifter motor. Oh ya I am new to this board and also just wanted to say hi.

 

Maybe remnants of valve stem seals.

 

To large for that. almosts looks lide maybe wear guides for the valve springs

 

Got a picture?

 

Crumbled remnants of a valve cover breather grommet? They start as nice soft rubber but get hard and brittle over time and many heat cycles.