Rust. The engine was painted with the manifolds on haphazardly so when the engine was fired the paint burned off and the manifolds started to rust pretty much since day one. If you don't liek that look have them coated...

The funny thing about science is that if you change one miniscule parameter you change the entire outcome to the way you want it.

JB Rhinehart, Realist

A-Body's RULE!