Quote:
Originally Posted by Tellyshavilli
AFAIK. 1971 455 Ho Heads casing number 191 we’re only cast in early December 1970 and early Jan 1971 all other 1971 455 Ho Heads will have no casting date
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I believe the earlier heads actually cast the date code under the valve cover, right where the center head bolt hole would be drilled. So when the head went in for machining, it drilled right through the date code leaving only the edges of the date code casting present.
My set of 197 heads is this generation. I have no idea when mine were cast since the letter/number combo is now gone, but I can see where it was cast. As I understand it, this was earlier in the production run. Later they went to casting the date code back in the usual spot on the rail, just below and outside the valve cover.
I'm sure OPH and others have a better understanding of these details. Hopefully they will chime in.
__________________
Eric "Todd" Mitten
'74 Bonneville 4dr Sedan (455/TH400/2.93 open)
'72 LeMans GT (455/M-13/3.23 [8.5"] posi)
'71 GTO Hardtop (400/TH400/3.07 12 bolt posi)
‘71 GTO Convertible (455HO/TH400/3.23 posi)
'67 GTO Coupe (455/ST-10/2.93 posi)
'67 Tempest Wagon (428/TH400/2.56 posi)
Deuteronomy 8:3
