[Indy8]

I believe it's like a fiberglass reinforced plastic or carbon compound fused onto a steel collar, but not positive. Another member of this forum tried to remove his and snapped off the end of the cam. You might have/want to have this done for you because of the consequences involved. The procedure includes removal of the valve cover to gain access for the puller, then heating up the collar to get it off. Then press on a new one and reassembly with a new v/c gasket. Is this thumping rotational as related to engine speed or any particular rhythm?