Subtle valve cover differences

[Conserv]

Thanks to Tom (@‘76mintgrun02) for finding the 2015 thread. Sadly, it’s much longer than I recalled… 😳

 

Six pages on valve cover styles? What a bunch of nerds! 🙄😋

 

Regards,

 

Steve

 

[Conserv]

8 hours ago, bob02 said:

Sure Marty, here you go.

The top cover was cast June 1971 (6 nubs surrounding “71”). I don’t see a date on the bottom cover. Am I missing it? I note that the “casting number” on the bottom cover ends in “6.9” whereas the top cover ends in “7.0”. Does that imply that the bottom cover is an earlier version? Maybe.

 

Regards,

 

Steve

 

[visionaut]

My 76 cover has the roundel in the center.

My polished cover has the roundel on the end (with the raised dot cylinder numbers).

 

[Conserv]

2 minutes ago, visionaut said:

My 76 cover has the roundel in the center.

My polished cover has the roundel on the end (with the raised dot cylinder numbers).

 

But, Tom, I’m obligated to ask: “What are their casting dates?”

 

Best regards,

 

Steve

 

[Son of Marty]

19 minutes ago, Conserv said:

ix pages on valve cover styles? What a bunch of nerds! 🙄😋

 

Glad to see you have finally woke up Steve, we all be nerds here.

[visionaut]

14 minutes ago, Conserv said:

Does that imply that the bottom cover is an earlier version? Maybe.

Just looking at the inner structural ribbing differences, I’d say the lower cover was newer. It’s looks to be the more advanced design ( note no stiffening ribs at the front at all, more weighted nodes, ribs not extended to the edges, more complexity in the rib pattern, etc).

 

<enginerding>

 

[Conserv]

1 minute ago, visionaut said:

Just looking at the inner structural ribbing differences, I’d say the lower cover was newer. It’s looks to be the more advanced design ( note no stiffening ribs at the front at all, more weighted nodes, ribs not extended to the edges, more complexity in the rib pattern, etc).

 

<enginerding>

 

Geez, Tom,

 

I was pretty impressed with my “6.9 comes before 7.0” theory…😢

 

 

[2002iii]

I have a whole bunch of valve covers in a couple bins somewhere. I need to dig them out and take pictures of all of them anyway, I'll post pictures of both sides of all the different versions I have.

[visionaut]

Looking at the old 6-page thread, I noted that Steve!s spare 76 cover is structural-rib identical to the upper cover here, even though that’s a 71…

 

Methinks there’s gotta be multiple suppliers mixed in along with the years variations.

 

[Conserv]

6 hours ago, visionaut said:

Looking at the old 6-page thread, I noted that Steve!s spare 76 cover is structural-rib identical to the upper cover here, even though that’s a 71…

 

Methinks there’s gotta be multiple suppliers mixed in along with the years variations.

 

+1

 

And maybe that better explains the lack of a casting date on a few of the ribbed covers: different suppliers.

 

That un-dated cover also lacks a tiny BMW roundel on the underside. Is that because (a.) some suppliers didn’t add the roundels (used, at some point, to verify factory parts), or (b.) the roundel was only implemented or mandated at some date after it was cast.

 

I’m guessing “KN” is the manufacturer, or foundry, of the un-dated cover.

 

The ideal nerd — I mean “meticulous researcher” — for this project would capture all this cast-in data: dates, casting numbers, manufacturers’ marks. 

 

Denvertii probably has no idea how close he was, given his vast inventory, to becoming the world’s ‘02 valve cover expert! But, oddly, he didn’t appear to have any un-dated examples. Hmm… 🤔

 

Thanks,

 

Steve

 

[jimk]

This thread is so enamored with valve cover designs;  why did BMW have so much webbing cast into the underside of the covers?  I have my guess, how about yours.

['76mintgrün'02]

21 minutes ago, jimk said:

why did BMW have so much webbing cast into the underside of the covers?

 

Aside from adding strength, do you suppose the ribs are placed so they're self basting?

 

[visionaut]

2 hours ago, Conserv said:

But, oddly, he didn’t appear to have any un-dated examples

Yes he did. His ‘mystery’ cover - which is an E21 “i” cover, had no date.

 

I’d most like to look at the underside on his ‘all lower case’ zündfolge cover though... He lists the dates for all of them pictured at the top, I wonder if it’s possible to figure out which is which?

[TobyB]

+1 for Tom- you gotta keep your rockers basted.  

It's one reason they break at high rpms-

the passive basting system can't keep up much over 6500.

 

t

 

[bob02]

12 hours ago, Conserv said:

The top cover was cast June 1971 (6 nubs surrounding “71”). I don’t see a date on the bottom cover. Am I missing it? I note that the “casting number” on the bottom cover ends in “6.9” whereas the top cover ends in “7.0”. Does that imply that the bottom cover is an earlier version? Maybe.

 

Regards,

 

Steve

 

Close Steve! That’s the original form my 5/71 production 02. Interesting that the two have different part numbers and the lack of contour to the inner ribs on the mystery valve cover.Now I’m wondering if it will clear the oil spray bar bolt and Hans mentioned! 
 

Bob