Bolt on timing chain tensioner
I think the nylon...plastic....whatever you wanna call it, like everything else has improved over the decades. The nylon that was on factory camshaft sprockets back in the day was hardly what the polymers of today are. Even 30 years ago was light years ahead of the polymers of the 1960s and 70s. When I was working for the local Chevy dealer back in the late 80s, I went to the GM training center in Atlanta several times and even then they were talking about polymer engine parts. Crankshafts, camshafts and on and on. So it wouldn't surprise me to see that some day. Just look at the space program. They've been using badass polymers there for decades.