That's supposed to be 'identification' above.

I have a 72 Cutlass S with 350 engine and just noticed that the left head is marked "7A" and the right head is marked "7". I believe they both might have the same part number (but the right side head number is covered by the exhaust shroud). The engine was recently reworked. Is this a problem?? Did somebody swap one of my heads out? Could the heads come like this from the factory? (Note: I am the original and only owner, ordered the car in 1971, and I'm certain the heads were never removed until the recent rebuild). Can somebody school me on the differences between a '7' head and a '7A' head? Am I in trouble here? Did somebody pull a fast one on me? Should I panic now and avoid the rush later? Time to call a lawyer?
Thanks for any info!

 

Wow, I would talk to the shop that did the rebuild. I would also check the block stamp pad and make sure I got back my original engine.

 

7 and 7A are nearly identical, so I wouldn't worry any about it.

 

Check to see if they are different heads......7A or 7. Then check the engine serial number.

 

Thanks to all for your replies. Since my post, I found this article at https://oldsjunction.classicoldsmobi...sfaq/ofhed.htm with a substantial discussion about Olds heads. According to this info:
Yes, the 7 and 7A (with a subscript A) heads are virtually identical. They even have the same part number. 7 was used in 1971, 7(subscript)A used in 1972. The 7(subscript)A had hardened valve seats but the
7 supposedly did not. Since my rebuilder claims to have used hardened seats in the rebuild, I guess it's a non-issue. My car was built in Aug 1971, so maybe they had some '7' heads laying around from the 1971 production line, and decided to put them on my 72 as-is, or maybe they reworked them and put hardened seats into the 7 head, so I got hardened seats all around. OR the rebuilder did it. Whatever, it's been working adequately in my daily driver application for over 50 years and hopefully will go another 50.

 

I don't know what you are reading, but ALL Oldsmobile heads from the 1971 model year on came from the factory with induction-hardened valve seats, since the feds required low-lead gas starting with the 1971 model year. That means that both #7 and #7A heads have hardened seats. This induction hardening only goes a few thousandths of an inch deep, so the first time the heads have a valve job that layer is cut off anyways. No, Olds did not randomly install different leftover parts on the assembly line. Any time this was done, there was full factory documentation, since Olds had to maintain a parts and service network to support these cars under warranty. There are OTHER cases where part substitutions were made, and these are fully documented in Technical Service Briefs and the parts books. The only fundamental difference between #7 and #7A heads is the valve spring pockets. The #7 heads used rotators on the exhaust valves only. The #7A heads used rotators on both intake and exhaust. That means that on the #7 heads, only the exhaust valve spring seats are cut deep, on the #7A heads all spring seats are deep. This means that if you have deleted the rotators, the deep pockets need to be shimmed to achieve the correct installed spring height and seat pressure. Be sure this was done.

 

Joe, Thanks much for your explanation. Is it possible to learn if the car had the 2 different head types on it from the factory? I never got the build sheet for it. If it's possible that it came from the factory that way, then it's certainly possible that I did not notice it for 51 years. I'm inclined to think the rebuild shop did it. I did get the numbers off the block and confirm that the original block is still in the car, so that's a good thing. The heads have me perplexed. I'm in the process of trying to get details of the rebuild.
Bonus info: I took pictures of the engine bay prior to turning it over to rebuilder. Later, my phone got smashed by a truck (literally) and all pictures lost. I had no backups. Those pictures may have been able to quell my suspicions.
Barry

 

Yes, there is no fuzz on this. The heads were the same when the car left the factory, period.