Subtle valve cover differences

[kbmb02]

I have a NK valve cover with the same numbers...

 

 

 

 

(Any NK owners looking for one? Message me.) -KB

[visionaut]

On 8/9/2024 at 10:16 PM, Conserv said:

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

 

Best regards,

 

Steve

 

LOL. Ok, Steve, I dug out my old cover with the roundel in the center. While it was ‘originally on the car’ when I bought it, it’s NOT an original 76er cover… (You’d think by now I would’ve guessed that!).

 

It has an 82-83 casting date 🤭 and a different identifier ( not 118 026 xxx). But it’s a 7.2!

 

 

[NickVyse]

28 minutes ago, kbmb02 said:

I have a NK valve cover with the same numbers...

 

 

 

 

(Any NK owners looking for one? Message me.) -KB

 

That's a 1964 only cover due to the unique crank case breather. '63 and '65 were different.

 

[NickVyse]

4 hours ago, Conserv said:

Thanks, Nick,

 

Is this example ribbed? And is it dated?

 

 

 

 

Sunday afternoon nerd just pulled my two smooth covers from '65 and '66 - had asumed they were different for the with and without oil spray bar spec, but appear identical - earlier one has a 'C' stamped under the number, but neither have a date stamp. Both have KN on the cast.

 

You can see how little I had to clearance the cover for the spray bar - obviously there's enough variance in the height of the spray bar for some to fit and some to foul.

 

 

 

 

 

 

 

Taller spray bar?

 

Lower spray bar?

[TobyB]

The numbers cast into a part are seldom an actual BMW part number.

 

A casting number is very different from a stamped number, which is added later.

 

The ribbing probably does a very good job of trapping and de-aerating oil spray.

 

I can't believe I read all the way to page 4....

 

t

 

[visionaut]

45 minutes ago, NickVyse said:

 

That's a 1964 only cover due to the unique crank case breather. '63 and '65 were different.

 

The NK cover I shared also had that unique breather. So also a 64, same cover as KBs.  

[bob02]

49 minutes ago, TobyB said:

The numbers cast into a part are seldom an actual BMW part number.

 

A casting number is very different from a stamped number, which is added later.

 

The ribbing probably does a very good job of trapping and de-aerating oil spray.

 

I can't believe I read all the way to page 4....

 

t

 

I like what you’re saying about the casting numbers, Toby. I pulled another valve cover off the garage wall and this one has the roundel and date(5/71 and upside down!) and yet another different casting number! 
    Think I’ll pull the one on the car next and see what lurks beneath. What a nerd fest!Let’s get to page five😂

 

Bob

[Conserv]

2 hours ago, TobyB said:

 

I can't believe I read all the way to page 4....

 

Toby,

Like they always say, “If you find yourself on page 4 of a valve cover discussion, you just might be a nerd…” 😯

 

I suspect the conclusion here will be darned close to what you said on page 1, “there’s probably 12 different styles”…👍

 

We weren’t looking to the final casting numbers as part numbers, but simply as a potential aid in placing the covers in chronological order, or something!

 

Best regards,

 

Steve

 

[Son of Marty]

Most likely the casting numbers are to keep track of the casting molds so tnat if one set starts to miscast parts they will know which one needs to be rebuilt, and yes molds do wear out over time. The same goes for blocks and other castings.

[visionaut]

2 hours ago, Son of Marty said:

Most likely the casting numbers are to keep track of the casting molds so tnat if one set starts to miscast parts they will know which one needs to be rebuilt, and yes molds do wear out over time. The same goes for blocks and other castings.

Mold numbers - exactly. Specifically BMW-assigned mold numbers issued to the suppliers to control a particular inner/outer mold combo.  So why we find same inners with different outers..

 

The same ‘scheme’ was used at BMW Motorrad during the same time period, with the identification prefix format:  xxx xxx x with an added 2 place assigned version number.

 

Also discovered : BMW wouldn’t change a mold number if parts were interchangeable via multiple suppliers - only if it’ a part is replaced outright with a better, improved version. That might also explain the ‘extra’ supplier marks…

 

 

Lastly, the E21 “i” (320i) covers with the pad being at later top-bottom new design, have even shorter height curved ribs -- structural design improvements?  or just that later E21 suddenly needed less “basting’? (srsly, they’d spend big extra $$$ to cast in node-weighted internal ribs just to aid oil splashing? That’s a freebie.)

 

I didn’t go pull my cover like Nick, but spent me a little nerd -time digging into period BMW manufacturing…

 

Tom

[visionaut]

Pics of the E21 320i cover with the short ribs. It has the different 1 251 140 assigned mold number. Note also the addition of extra ribs/nodes where the added idle valve sits… for extra basting? (not)