Tyler wrote: Any marks on the camshaft bearing surface? If not, don't touch a thing. Put it back together.
I agree. If this did happen during a service, it seems to me the biggest risk would have been that the fractured surface at the edge of the journal would have a sharp edge that would mar the bearing surface on the camshaft. If the camshaft is clean, then there has not any interference in the past, and there should be no interference in the future. Seem to me that if you put it back together as is, it would continue to work just fine. Messing with it is just as likely to introduce a problem as it is to fix one.
I don't think the loss of that small part will compromise the strength of the cam journal. The only other thing I can think of is that oil might not stay in the journal as well as it normally would, since it doesn't have to travel as far along the bearing surface to escape. So maybe this journal could end up with accelerated wear, but that seems pretty unlikely.
