Casting Flaw on Finned Valve Covers

[Guest]

All - a friend recently purchased a 1966 Corvette (December B Day). When did the casting flaw began to appear on the the finned Aluminum covers and for NCRS judging is there a deduction? I understand it was in 1966, but not sure when. Thanks

[William C.]

Re: Casting Flaw on Finned Valve Covers

Approximately mid-year, but as to deduction, it varies with the significance of the flaw. Originally the actual flaw in 1966 (and '67 for that matter) was quite light, and not real nitacable. As time went on, and many were ordered thru service, the tooling deteriorated to where the center of the "O" in Corvette was partially filled in and the seam line was quite pronounced. Those were not representative of the factory installed items and would be treated as a service replacement. There is also a large grey area between the extremes that must be navigated by carowner and/or judges.

[Guest]

Re: Casting Flaw on Finned Valve Covers

Thanks

[John D.]

Re: Casting Flaw on Finned Valve Covers

Eric, Bill Clupper is correct of course with his answer. About March 66 is when the casting flaw (crack in mold) finally broke thru. That's what I have been told when I researched the valve cover info. But as Bill said there had to be overlap on the installation of seamed vs no seam. John