[thepontiacman]

It has ends of date code casting where inner center head bolt hole was machined like the RA IV.


I think it's a early production example.

I have had several over the years but don't find them much anymore.

What do you think?

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['ol Pinion head]

Early production '71 HO heads indeed had no external date codes, the center head bolt hole machining process removed the casting core date code. Sharing the same fate were production installed '722's & 614's.

"Late" 71 HO heads began to be cast Dec 4 (L040). The 4th was a Friday, & in over 3 decades, I've only ran across a few cast on that date. The following week, a good sized run of L080's were cast, then again on Jan 8th.

Have often examined an original mid to late production '71 455 HO factory assembled engine with an L080 & an A081 dated head. So many times, its more of the norm. Those two dated heads, paired together, is very common on factory assembled HO engines assembled through the late Winter & up through the Spring of '71.

With a few assembly plants still shut down from the Fall UAW Strike up into mid to late Jan of 71, & with HO engine stock on hand at them, those plants used up what assembled HO engines were on hand & the result is what some don't understand, the factory install of 9799140 casting early '71 HO engines in into Feb assembled HO cars coming out of very low production plants like Framingham & Oshawa, as well as higher volume HO install plants like Norwood.

[thepontiacman]

Thanks for the detailed info.!

[PAUL K]

Any chance you could post a close up of a single combustion chamber without the valves installed? The over the counter RAIV XC heads had completely different ports (area under the valves) than the original service heads. The 197 head looked just like the RAIV XC heads if you milled the chambers about .200 deeper. I always thought Pontiac used the same XC casting for both the RAIV & 197 head. They just machined the chambers deeper on the 197. The 7F6 and SD were both separate castings. The SD was an updated 7F6 casting and had internal support bosses to prevent cracking that was common with the 7F6 heads and RAV.

[thepontiacman]

Here you go.

I can text them if needed. PM number.

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[PAUL K]

Originally Posted by thepontiacman

Here you go.

I can text them if needed. PM number.

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Thanks a bunch.... I will send you a PM

[thepontiacman]

Back together after checked.

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Pics show one paired stud boss. Others separate

[eaglesan13]

I've owned two 1971 birds with 455HO's in them. One was a Trans Am and the other was a Formula 455HO. Both were built the second week of February 1971 in the Norwood plant. Both cars had their original cylinder heads. Both heads in the Formula were undated. One head in the Trans Am was undated while the other was dated mid December (either L130 or L160, I forget which).