Timing Cover date codes

[Z10Mike]

Looked through all the threads on this subject and could not find a definitive set of guidelines for small block vs big block timing cover date code format.
So far the codes are supposedly week and year of production i.e.  21 69 is 21st week of 69, Julian calendar date vs year i.e. 21st DAY of 1969 or even MONTH of production vs year.  It also appears to vary from small block to big block . Can any of the guru's here summarize what the latest tribal knowledge is on these date codes?  THANKS...

[MO]

I recently sold a small block cover dated A 67.

[ZLP955]

On my work bench I have 2 of these, one is '34 69' and the other is '13 70'. Unless there were different date formats, I think the "month, year" format could be ruled out. If it was "Julian date, year" I would expect to see many with a 3-digit date, followed by year, but have never seen an xxx yy stamp, only xx yy (anyone else seen an xxx yy stamp?). So maybe it's "week, year", and if so, is it production week of model year (like gas tank date stamps) or calendar year weeks??

[JohnZ]

I have a '69 DZ cover on the bench stamped "4 69", so it looks like the format is week/year, with the week most likely calendar, not model year.

[Mike S]

Where on the BB cover is the date stamped? I'd like to look at mine.

Thanks,
Mike

[1968 Z28]

I have a 1968 Z28 cover that is stamped "3 68".

[1968 Z28]

Where on the BB cover is the date stamped? I'd like to look at mine.

Thanks,
Mike

Mike.....can't say about the big block covers but if they are like the small block covers, you can only see the dates with the harmonic balancer pulled.  The best way is to have it removed, cleaned, and on the bench.

[KurtS]

I have one that is stamped with a different format. If I recall, it has a letter in it.
I won't be around it for a year, so I can't say the exact code. I think I posted the code before, but not positive.....

[Z10Mike]

It sure looks like the small blocks are trending toward the week of production and year.  "3 68" would be 3rd week of calendar year 1968.  Could big blocks use a different format?  Kurt mentions a letter in the mix.  Was that for small block or big block?

[Z10Mike]

Anybody out there with information on big block timing covers?  I might have a chance to dig through my parts this weekend and find a couple of examples to compare to others if posted.  Thanks to all who have commented to date.

[KurtS]

It was a small block 69, big balancer. Might not have had a letter, but IIRC the week # was way too high / no year. Damn, that memory is fuzzy.

[ZLP955]

Here's a 1969 dated BB timing cover, currently listed on ebay: http://www.ebay.com/itm/290976608998
Seems to follow the same date code format as the SB covers I have, if the stamp is '31 69'. If the '3' was upside-down, instead of the '1', then the date code would be '69 13' which is possible, but has anyone ever seen the year stamped first? (Date code images below)

[Stingr69]

There was more than 1 way to stamp a cover date.  I can't remember the exact details but I did have an email conversation with Jerry M. about it years ago.  I had a big balanceer SB cover with an odd date stamp.  He has seen some julian dates and some that just are clearly not Julian that he could not decode. My cover was not originally on my car so I never recorded the stamp, sorry.

-Mark.

[69Z28-RS]

I have one that is stamped '1   67' ..   which is obviously NOT Julian date (unless they worked on New years day?) *G*  but it *might* be for the first week of Jan...