[A26B]

Originally Posted by Paul Workman

Sitting here sippin my coffee, I just remembered that story from the HOTB book, where this gal was cranking up the brand new ZR-1s in sub freezing temps with the accelerator nearly floored. The result was a number of new ZR-1s with cam failures. So, it seem a quite plausible notion that most of the wear over time goes hand in hand with cold, dry starts, sans pre-oiling..................

That's just part of the story.

As related to me by Graham Behan.
Upon investigating this problem, it was discovered that the cam journal & corresponding journal bore tolerances were at fault, but certainly exacerbated by the starting procedure. All machining dimensions have tolerances, or a range of acceptable size. The size usually varies from tool wear and the machine tool accuracy. Such is the case here. As it turned out, clearance from the cam journal diameter at the large end of the tolerance and the journal bores at the small end of tolerance was insufficient. Revising the dimensions & corresponding tolerances solved the problem, right along with the cold start procedure.