Information on why I think lead is bad for the valve guides.
https://www.ntsb.gov/safety/safety-recs/recletters/A87_71_76.pdf
https://aslcamguard.com/wp-content/uploads/Camguard-Parts-1-to-3.pdf
https://www.ntsb.gov/safety/safety-recs/recletters/A87_71_76.pdf
https://aslcamguard.com/wp-content/uploads/Camguard-Parts-1-to-3.pdf