[bill ryder]

Sorry, Haven't paid any attention for the weekend. I need to correct myself. Originally I thought the X and O was on the same boss, not one on each. So what I said before is not correct.
I've tried to upload a picture with no success so I will explain:
My X is on the right hand side of the LEFT dime sized boss. Not centered. The right hand side dime sized boss is almost empty with just a small arc on the top side about 2 o'clock position. Could be part of an O. I can't say for sure. The other head is completely void of marks. SORRY if I got you going in the wrong direction!!!!!!!!!!!! "Bill"!
Just found the head pics I took in 1990. Both heads date code is C254.

[John V.]

Bill, thanks for clarifying your stamp marks.

The fly in the ointment would appear to be the early XX stamped Heads.

If all late 9770716 Heads were the same and if at least some of them were stamped XO (notwithstanding Bill's example lacking any stamped marks and his example that was stamped off center so that the marks aren't clearly interpreted), then logically the early heads stamped XX must have been intended for the 389 GTO (the '64 10.75 cr 389 big car tri-power engines are way too rare to know whether they shared the GTO Heads or the 421HO Heads early year but since there is no mention of early & late valve spring choices for this big car engine, I suspect it should have gotten the 421HO Heads and not the GTO Heads for the entire year).

But the only known 421HO example is b-man's and it is stamped XX. Either my interpretation is wrong or else that early '64 421HO engine was incorrectly assembled with the GTO Heads having standard valve springs.

b-man, if you have the tools to check it and if the valve springs on your 421HO Heads are still the originals, you could measure the wire dia. for the inner and outer springs to see if they match the standard or HD spring dimensions.

That might help point to a conclusion.

[John V.]

Follow up to my own earlier post with the Engine Spec pages, this WAS published as a News Flash in case anybody wants to hunt for it.

News Flash No. 64-95, dated 5-1-64.

[b-man]

The 421 HO heads stamped 'XX' have the standard valve springs, .162" outer and .120" inner wire diameters.

The 389 GTO heads stamped 'XO' have the HD springs, .170" outer and .141" inner wire diameters.

I used some dial calipers to measure them.

Everything looks to be original on both sets of 9770716 heads.

[John V.]

b-man, that is excellent and I think is pretty compelling "proof" of the actual difference between the XO and XX heads.

Since the early GTO Heads are the only version identified in the published PMD documents that were supposed to have used the standard springs, my guess is that your 421HO was built with the XX Heads by mistake. No indication that the 421HO Heads were ever supposed to use the standard springs and given that they were a carryover from '63, very doubtful the standard springs were intended for the 421HO Heads.

It even occurs to me that the existence of 2 flavors of these Heads made such an error probable and may have been the reason to change the GTO Heads (rather than any failure problem that may have materialized in the first few months of production).

Wonder how many other early '64 421HOs got the XX Heads (and for that matter, I wonder if any early '64 GTOs got the XO Heads).

Had given up trying to discover what those stamped codes meant. Neat to finally get some compelling evidence.

[John V.]

W.E., new info?

[War eagle]

These show the part number difference. One setting on later pad vs. early no pad or platform.

[War eagle]

Phoenix is usually warmer than this but it did warm up a couple nites ago at a friends shop. 4 sets of 716 heads appeared and I took the opportunity to get some pics and observe differences.
There is no left or right head as one casting can be used for either side. However it must have been interesting to see the amount of 716 foundry patterns used during a pour.

The earliest, L32, is cast upside down,(compared to part number) and has X and O stamped at the button pads at the center exhaust ports. To the very end and right of the cast part number, is a small pad that has a line as shown with my pen in the picture.

The next pair J193, is cast upside down and has X and X with the end button pads having a line on one head and + on the other. I suppose one could say plus or minus.

E84 pair has the date upright and has X and O at center exhaust port. The end button pads are + and +.

E224 and E254 are different at the exhaust port. Dates cast upright. A fair amount of rust on 22 but looks like O and X. E254 has nothing in the first exhaust pad but looks like the O above two X`s on the second pad. Again there is a bit of rust but visable under a glass. The end button on 25 has the + and the 22 has the minus.

Not sure if this helps or what the end buttons tell us. Maybe day or nite but these are not stamped but cast in. Foundry number 1 is on all of the heads so it is likely only one line cast heads.

I was promised access to 5 different 1964 trips manifolds so that will be next week.

[johnta1]

Interesting on the end pads.

[Brad_bb]

Ya'll need to get those pics more in focus.

[John V.]

Originally Posted by War eagle

These show the part number difference. One setting on later pad vs. early no pad or platform.

2nd pic is blurry. I don't understand what you mean by a "part number difference"?

The + and - marks out on the ends is interesting but since they are cast in, doubt they mean much. Wonder if these same + and - marks are common on all '64 heads in that location. might not be unique to the 9770716 heads.

[War eagle]

Originally Posted by John V.

2nd pic is blurry. I don't understand what you mean by a "part number difference"?

The + and - marks out on the ends is interesting but since they are cast in, doubt they mean much. Wonder if these same + and - marks are common on all '64 heads in that location. might not be unique to the 9770716 heads.

The difference of course is the lack of a pad under the early 9770716.

I doubt if the foundry guys would agree with you regarding the end cast marks. They DIDN`T do it if "they don`t mean much". Kinda sad John

Hoping other 64 guys with the 716 and those end marks could give us some dates and their + or minus. I am betting on nite or day shift. I would have thought the foundry pattern number would be part of the casting but I don`t see anything else.

[John V.]

Originally Posted by War eagle

The difference of course is the lack of a pad under the early 9770716.

Must be obvious by eyeball, I can't see any difference in the pix. Will have to look at my own pair, one about J303, the other about E154 IIRC. But won't get a chance to do that for awhile.

Originally Posted by War eagle

I doubt if the foundry guys would agree with you regarding the end cast marks. They DIDN`T do it if "they don`t mean much". Kinda sad John

Hoping other 64 guys with the 716 and those end marks could give us some dates and their + or minus. I am betting on nite or day shift. I would have thought the foundry pattern number would be part of the casting but I don`t see anything else.

Sheesh. I'm SURE it was important to foundry production. But it isn't important to a hobbyist to know if the heads were cast day or night shift. When they were cast would not mean when they were machined or when they were assembled. It would not help understand when the engine was assembled. And it would not impact when the car was assembled.

My comment was intended to mean that I doubted these marks mean much to us today.

I doubt they will tell us anything that can be associated with the application for the heads, or a particular engine, or a specific car build.

I ALWAYS find it interesting to learn about details such as the + and - marks you've posted about. But they aren't always of any real use.

And because I think they are probably of some generic meaning (such as you've suggested being day or night shift), I suggested looking at the standard '64 heads to see if the same marks are found on them. No reason to limit the research to the 9770716 heads.

I'm not able to look at my own 9770716 heads now, but do I recall perhaps a clock indicator near the cast date tag under the valve cover? Any other cast identifiers there?

Later model heads got a variety of cast identifiers external to the valve covers, including the cast date and a D-N shift indicator. Wouldn't surprise me that the '64 heads included similar cast identifiers in a different manner.

What would be an example of a foundry pattern number? Is that typically found on other Pontiac iron castings?

You mentioned Foundry number 1. I thought Pontiac cast all their heads at their own foundry at the Pontiac complex. What would Foundry number 1 represent?

[War eagle]

QUOTE FROM JOHN V "I'm not able to look at my own 9770716 heads now, but do I recall perhaps a clock indicator near the cast date tag under the valve cover? Any other cast identifiers there?

Later model heads got a variety of cast identifiers external to the valve covers, including the cast date and a D-N shift indicator. Wouldn't surprise me that the '64 heads included similar cast identifiers in a different manner.

What would be an example of a foundry pattern number? Is that typically found on other Pontiac iron castings?

You mentioned Foundry number 1. I thought Pontiac cast all their heads at their own foundry at the Pontiac complex. What would Foundry number 1 represent?[/QUOTE]



Foundry pattern number----Why sure. Grab your iron distributor and look at the stem. Grab your original cast camshaft, although not a GM manufactured part. Check out your cast crank.
Outside other than 9770716, is GM on one end and 1 on the other. The block has GM 2. I assumed from the Chevelle and Camaro forums that these were "foundry" lines where individual components were cast. In other words, certain components are cast on different lines. In this case, heads on one line---blocks on another. I visited the New York Tonawanda GM Foundry when it was still going hoping to see some BIG BLOCK 427 Chevys being cast. THAT was a HUGE operation. No way to see exactly what was cast on that day but you knew that engine blocks were being cast on that line.

Sorry about those poor pics. Nobody at the gathering had a better phone cam so we suffer with that Polaroid until I recover from my donation to PY and the 2900.00 order. Hee Hee there goes Christmas!!!

[b-man]

Originally Posted by John V.

2nd pic is blurry. I don't understand what you mean by a "part number difference"?

The + and - marks out on the ends is interesting but since they are cast in, doubt they mean much. Wonder if these same + and - marks are common on all '64 heads in that location. might not be unique to the 9770716 heads.

Not unique to the 9770716 heads, my 9773345 326 heads have those same markings on the end pads.

[Brad_bb]

Not sure if this helps, but here is a video of my five 716 heads. Note, one head has the "O" and "X" on the same dime shaped pad.
http://youtu.be/Y10tU0rquec