291 heads production question

[JHS]

I have a set of 291 heads, cast date E070 (the last "0" is quetionable but pretty sure that's it), correct single "hump" casting symbol, HI-PERF casting but there is no "T" for Tonowanda anywhere to be found. There is a "GM1" casting but no T after it. There is also what appears to be "CDF" casting code. Are these service replacement heads? Where would they have been cast?

[Mr70]

Those were cast at the Saginaw,Mi.foundry.
I have a few like that & are actual assembly line parts.
They date coded their components differently then Tonawanda.
E stands for May.
07 is the day.
0 is the last digit of the year casted,1970.
I think you mean CFD,which stands for Central Foundry Division.
The Saginaw foundry provided mostly Flint-(i.e smallblock),with it's components,but Tonawanda-(i.e.bigblock),also borrowed from them too.

[JHS]

You are correct, it is "CFD". From what I read I thought all bb heads were cast at Tonowanda. Thanks for the clarification.

[Rixls6]

I have a set of "188" big block heads that have casting dates and codes like that, but thay are from a 1990 engine.

[Ls6 Ragtop]

I'm with Rixls6 on this one. Don't think I've seen a 1970 casting quite like this. All 1970 castings I've seen have the 70 for the year, not just the 1 character 0. I've never seen 01-09 used for the first 9 days of production either on the early assembly line stuff. It would most likely be 1-9. For this head to have been dated May 7 of 70 the casting date should be E 7 70. 69 dated heads do only carry one digit for the year i.d. so K 28 9 would be Nov.28 1969. From jan of 70 on throughout production GM used 70 for the year designation.
That being said, the casting date without seeing the heads could be either the first 0 might be another character such as an 8 maybe, or most likely the heads are from 1980 or 1990.
Chris

[JHS]

Thanks Rixls6 and ls6 ragtop. I wondered about this also as Colvin stated the year would indicate "70". My heads are in fact cast "E070" so may, in fact, be 1980 or 1990 castings. Since no "T" on them, as Colvin also said there would/should be.