adis

Looking at the heads on my stock '72 SBO i can clearly see the pass side 7A,



but on the driver's side it is not clear.



Is that raised area next to the top of the "7" what used to be an "A"? Did the two sides have different castings like that? I've read that it is a "subscript A" not superscript. Is the driver's side head a 7 or 7A? Thanks!

Tony72Cutlass'S'

My Drivers side has a 7A head. I am 100% sure.

My guess is that your drivers side was replaced somewhere along the way? By the way, #7 heads are from 71' ... Look at the tech section

7 --> '71 350 64 409147 W-31's had larger [2.000] valves.


7A --> '72 350 64 409147 The 'A' is a subscript

adis

Thanks for the reply, Tony. So your driver's side "7A" is clearly cast just like the pass side? That's what I'm wondering, if the driver's side is a 7 then that likely means that it was replaced at some point (which I was not aware of when I bought the vehicle from the original owner.) Unless, at whatever point my serial 167424 VIN car was made in '72 they mixed and matched 7 and 7A heads.

MDchanic

You've got a #7 and a #7A head.

Probably one was changed at some point.

They should be functionally the same.

If you want to confirm, there should be casting date codes on them somewhere, but I am not the one who knows where to look - they should be very roughly a year apart.

- Eric

adis

Thx Eric

Tony72Cutlass'S'

I could take a picture but i'm at work right now, But yes, it's clearly stamped 7A and the A is underneath that little screw thing you posted above.

As eric said, they're both functionally 64cc heads. So all that's different is that little A stamped under the 7. If your car is running well i'd say just to leave em' be.

hookem horns

I think the A just indicated hardened valve seats for unleaded fuel in 72.

joe_padavano

The 7 and 7A heads start with the same casting, but the difference is in the machining for the valve spring pockets. The 7 heads have deep pockets on the exhaust side only for rotators. The 7A heads had rotators on both intake and exhaust, so both have the spring pockets machined deep. If you are rebuilding the heads and are getting rid of the rotators, you can shim the deep pockets to get the installed spring heights all the same, or conversely machine the shallow pockets to match the others and run taller springs to allow more valve lift before spring bind.

Tony72Cutlass'S'

Although, your passenger side head seems a little bit wet with oil, have you tried torquing down the gasket in a criss cross?

joe_padavano

No. ALL Olds heads from 1971-up came with induction hardened seats due to the federal requirement to use low-lead (and later no-lead) fuel. There were CA heads in 1967. These did NOT have hardened seats.

adis

Thanks for all the replies guys - Especially your valve cover comment, Tony...(joke)

I'm not concerned about it or planning on doing anything right now. i was just going through my "here's what i wish i could do to my cutlass" plan, rebuilding the engine in different configurations in my mind; and I noticed the different heads. i've been thinking that the new(er) generation of carb port intake, easy EFI products sound too good to be true (except for the price) I was imagining a SBO build with one of the easy EFI products, a Performer RPM intake, mild cam, (got the exhaust already) and hmm, what heads? with the EFI, I've got to use an electric fuel pump anyway, so why not some AL BB heads? but to save money to afford the EFI, maybe I just refresh my existing heads, since I'm only looking for street performance (albeit great street performance.) Blah blah blah .. thanks again guys

Warhead

What Joe said is correct, but I would NOT machine the shallow pockets on the one head to match. There is only .200" material there, and you would machine a substantial potion away to make them match, it may risk cracking the casting under the spring if done.

I would find a match to the 7a head, myself, but most people who do not even pull valve covers would never even know the difference till they sold the car anyway. Not even worth the bother if you ask me.

The stock untouched 5,6,7,and 7a castings will be from 68-70 cc's if they have never had a valve job done on them.
64cc's is another internet myth that keeps getting it's can kicked down the road by some. MEASURE the castings. PRODUCTION stuff is 68-70 cc's.
Good luck to you.

cdrod

I always thought the hardened seats came in '72 with the #7a heads. I had a '71 Supreme with #7 heads, my engine builder cut down the exhaust spring seats and used the rotators on both intake and exhaust. Didn't have any problems with casting thickness, seems there was plenty of metal to do this safely. However, I did have problems with the exhaust seats not hardened. After about 1 year of daily driving, the engine started to lose power. Turns out, my #7 heads didn't have hardened exhaust seats, and the exhaust valves were literally sinking into the ports. I picked up a set of #7a heads and transplanted the hardware from the #7's with a fresh valve job and drove that car for 10 more years.
--I should of kept that one!

Allan R

72 does have 7A heads. I just looked at my car (original eng/heads). The 7A on the passenger side is by the #8 cylinder; the 7A on the drivers side is by the #1 cylinder

joe_padavano

And as I said above ALL Olds heads from the 1971 model year onward DID come with hardened seats to allow the use of low-lead fuel as mandated by the Feds. Keep in mind that Olds did not use hardened press-in seats. Instead, the cast iron head was locally induction heated around the valve seat to harden it. The hardening is not very deep and if the seats have been cut during a valve job it's likely the hardened material was removed.

Via3d

Old thread but inline with my questions, so I thought appropriate to ask here.

...Is the valve spring pocket differences and the ""Rotator style spring retainers were used on ONLY the exhaust springs"" the only difference in 7 vs 7A heads?
......Which is better? (noob question)

...So I understand from this thread that all #7 and #7A heads are hardened valve seats.

[QUOTE]All 1971 350's use #7 heads.[QUOTE]
[QUOTE]All 1972 350's use #7A heads[QUOTE]
...Accurate I assume from OldsFAQ

I am obtaining stock #3, #7, & 4A heads I am getting with a 330 & 403 block.
I see the #7's came with either 1.880/1.567 and 1.995/1.624 valves.
I am eager to see it has the larger valves, however I assume the larger valves were for W-30's, right ? (which I do not think these are from a W-30).

~J

Fun71

The W-30 was a 455 big block engine. Big block engines used letter IDs, small block heads used number IDs.

As to which are better (7 or 7a) they are exactly the same from a performance standpoint.

joe_padavano

Rotators are designed to even out valve and seat wear, but at the expense of heavier reciprocating mass and thus earlier valve float. For performance applications most people ditch the heavy rotators and use normal retainers.


HAHAHAHAHA The Olds FAQ has many well documented errors. Amazingly, this time the info is correct. Even a blind squirrel...


Annnnd, we're back... If you got this from the FAQ, it's wrong. The only SBOs to use 2.000/1.625 valves were the W-31s, and there were no W-31s built in the 1971 model year. You can install the bigger valves in the 7 or 7A heads, but that machine work will remove the induction hardened surface of the factory valve seats.

It won't.

BLUZIN

Sooo, with a machined head the hardened material is removed. How much does this effect the head? I.E. heads machined for bigger valves, 1.995/1.62.... good?? Not good? It was a full rebuild, bored .30 over on a 350, adding a 204/214 cam.
Thanks! Sorry If this thread is to old?
Jack

olds 307 and 403

The sunken seats mentioned in this thread is one of the few instances of sunken valve seats. I have heard of very few issues with Olds V8's. I assume you are using cast replacement pistons if you are using the mild 204/214 cam in a rebuilt 350? The bigger valves will work fine but are useless if the machine shop doesn't use a bowl hog cutter to remove material under them. Good luck.