1967 L-79 valve cover flaw date?

[Tom W.]

Mine is Nov 66 built. The red N.C.R.S. book says early in 67 build the casting cracked in the o. How early? my Nov. 15th car v/covers are not. Am I ok with that per N.C.R.S.?

[Tom H.]

Re: 1967 L-79 valve cover flaw date?

I always thought the "flaw" first appeared in 1966 models. I was under the impression all 67's with this cover would display the flaw.

[Bruce B.]

Re: 1967 L-79 valve cover flaw date?

Tom is correct, the flaw appeared in "late production 1966" so all 67 Corvettes with the aluminum script valve covers should have the flaw through the "o" in Corvette.

[Thomas A.]

Re: 1967 L-79 valve cover flaw date?

My '66 L79, born on 3/14/66, has the flaw in the valve covers.

[Scott S.]

Re: 1967 L-79 valve cover flaw date?

Mine is Nov 66 built. The red N.C.R.S. book says early in 67 build the casting cracked in the o. How early? my Nov. 15th car v/covers are not. Am I ok with that per N.C.R.S.?

Tom, I had the same question a while back. To the best of my knowledge, the newest printing of the '67 JG (orange/red cover) is Winter 2005, Fourth Edition, Second Printing. On page 73 it says: "The valve covers are finned cast aluminum with the word 'CORVETTE' cast into the cover. Most cars have a casting flaw line through the letter 'o' in Corvette. Some early production cars may not have the casting flaw line."

The new 1966 Judging Guide (2010) should be more up to date on this subject and is fairly specific about when the casting flaw occurred, under "Option L79, 350hp", p. 92: "The valve covers are finned cast aluminum with the 'CORVETTE' script cast into the cover. A casting flaw line through the letter 'o' in Corvette appears at approximately VIN 17000 (March 1966)."

There were 27,720 Corvettes produced in 1966, of which 7,591 were RPO L79 (Corvette Black Book 1953-2010, Antonick, p. 53) and would therefore have the finned aluminum valve covers. I don't know how many L79s were ordered after VIN 17000 and I don't know when the production line used up their last pair of non-flawed finned aluminum valve covers.

I have read that some cars have one flawed valve cover and one without the flaw. Since it is a frequently replaced item, unless one is the original owner or bought the car used early on, it's hard to know whether the valve covers on a car today are the same ones it came with off the assembly line, or not.

[Thomas A.]

Re: 1967 L-79 valve cover flaw date?

Scott,

My car is VIN 16459 . . . both covers have the flaw. I believe they're original to the car.

Tom

[Scott S.]

Re: 1967 L-79 valve cover flaw date?

Scott,

My car is VIN 16459 . . . both covers have the flaw. I believe they're original to the car.

Tom

Hi Tom,

I wouldn't disagree in any way, just saying there are several variables to consider, along with the passage of time. Are you the original owner of your '66?

There are at least two scenarios that could skew the data if a survey was taken on this subject. First, 10s of thousands of flawed valve covers have been (and are still being) produced, so any car could have the flawed valve cover today as a result of being replaced at some point. Second (although I'm sure less common), any car could have finned aluminum valve covers without the flaws if a previous owner decided to find used or old NOS replacements that were 'pre-flaw', for whatever reason. I almost went that route myself, before I learned to like the 'flaw'

[John D.]

Re: 1967 L-79 valve cover flaw date?

Mine is Nov 66 built. The red N.C.R.S. book says early in 67 build the casting cracked in the o. How early? my Nov. 15th car v/covers are not. Am I ok with that per N.C.R.S.?

tom,

My October built 67 with an engine assembly date of 9/15/66 has one of each. The crack is very faint as compared to the later repros.

[Gary B.]

1967 L-79 valve cover flaw date?

tom,

My October built 67 with an engine assembly date of 9/15/66 has one of each. The crack is very faint as compared to the later repros.

John,

Have you had your car judged with one of each? If so, I assume you get a a deduct? My July build-date '66 has one of each, which I assume to be original, but for judging I'm going to go the path of least resistance and put on two with the casting flaw that I've had restored.

Gary

[Marlin F.]

Re: 1967 L-79 valve cover flaw date?

Perhaps this is not the proper forum for this discussion, but if one wanted to 'swap' flawed covers for those not flawed with other members, is there a means to facilitate such transactions somewhere on the NCRS site? I have an early-build '66 (1055XX) with the flawed covers. Perhaps someone needs them!

[George C.]

Re: 1967 L-79 valve cover flaw date?

I think the information we have all seen in the judging guides is probably correct, but I have to pose a question.

I have a late build 65, May 19 or their abouts. Both my covers have the flaw, and I am aware that there is every possibilty they were replaced.

But as I look at cars at local shows, and on ebay as well as other internet sites I see many if not most of the 65's with the "O" flaw as well.

So my question is why have all these covers been replaced? They don't rust, they are pretty rugged, and most Corvette owners change the oil and clean their engines?
Thanks,
George

[Scott S.]

Re: 1967 L-79 valve cover flaw date?

They do crack when the valve cover bolts are over-tightened...

[Bruce B.]

Re: 1967 L-79 valve cover flaw date?

Hi Tom,

I wouldn't disagree in any way, just saying there are several variables to consider, along with the passage of time. Are you the original owner of your '66?

There are at least two scenarios that could skew the data if a survey was taken on this subject. First, 10s of thousands of flawed valve covers have been (and are still being) produced, so any car could have the flawed valve cover today as a result of being replaced at some point. Second (although I'm sure less common), any car could have finned aluminum valve covers without the flaws if a previous owner decided to find used or old NOS replacements that were 'pre-flaw', for whatever reason. I almost went that route myself, before I learned to like the 'flaw'

Scott,
I agree with you 100%.
Once the tooling cracked GM continued to manufacture the valve covers for production and service replacement. As we know they were and still are a very popular valve cover for SBC engines.
I have a few sets which I bought over the counter (GM) before the tooling was sold to Paragon who as you mentioned still produces the flawed valve covers.
Other then the flaw in the "o" the tooling is really worn out. The condition of the ones I bought is really bad. Other then the flaw there is lots of flash, flow lines and knit lines. Very poor quality.
Bruce B

[Chris E.]

Re: 1967 L-79 valve cover flaw date?

tom,

My October built 67 with an engine assembly date of 9/15/66 has one of each. The crack is very faint as compared to the later repros.

My September built 67 (car # 183) with engine assembly date of 8/24/66 has one of each also.

Been through Regional judging once and not received a deduct for having one with and one without the flaw.

Car has been in the family since 1973, and the motor never had a valve job before we completely rebuilt it. I believe that the valve covers are original to the car.

[Stephen B.]

Re: 1967 L-79 valve cover flaw date?

Gentlemen
Just went to the garage and checked my original owner
August built 66 and what to my wonderest eyes should appear ,but two valve covers with a flaw thou the o. Therefore it is my opinion that all 67s and damn near all 66s should have flawed valve covers.
Stephen Barrett (21558) 59,66,71,73