Cylinder Head Casting Date M97?? What Gives?

[ko-lek-tor]

  Matching head is dated Sept (I) 1968. Never seen an M. But seems to me I have read something about an M casting date. I just cannot find it in a search.

[bertfam]

Bergy can probably elaborate since he was actually there, but M97 isn't a date code. It's a foundry pattern code used to identify parts that were made to evaluate a casting process change.

Ed

[Petes L48]

So apparently the heads followed the same "M" usage as blocks

"M"-Coded Blocks
 There is one exception to this convention that has been observed: some blocks have been seen with "M" cast codes. Research by the Saginaw Metal Casting Operations of GM Powertrain Division has found that these "M" codes are not date codes, but actually a foundry code used to indentify parts that were made to evaluate a casting process change. After evaluating the parts, the blocks would either be destroyed or released into production. There is no way to determine the date an "M"-coded block was poured.   
http://www.camaros.org/numbers.shtml#GM-InternalDateCodes

[ZLP955]

My CE 302 has a pair of M-coded 186 heads. I recall asking about them a long time ago, so you may be thinking about that thread. Will see if I can track it down.

[ZLP955]

Found that thread - turns out it was over at Team Camaro rather than here at CRG:
https://www.camaros.net/forums/15-tag-team/205047-head-casting-dates.html

[ko-lek-tor]

Found that thread - turns out it was over at Team Camaro rather than here at CRG:
https://www.camaros.net/forums/15-tag-team/205047-head-casting-dates.html

Thanks Tim. Knew I read it somewhere. Now we have record here.
Additional thanks to Pete, Ed.