help to identify these rockers

[deQuincey]

i am puzzled by this:



i am in germany, (just another working week in this beautiful country), and got a bunch of NOS rockers for the M30 engine, but despite being all of them same reference there are different colour marks on them, and the question is what does this mean ?

is this a similar case of the blue/red marks of the crankshaft bushings ? so are they really different ? or may i use these rockers alltogether ?

thanks

 

[Markos]

If I had to guess, they are used, not NOS. Somewhere there is a cam with corresponding paint on each lobe.

 

[deQuincey]

If I had to guess, they are used, not NOS. Somewhere there is a cam with corresponding paint on each lobe.

negative

 

[m5bb]

i am puzzled by this:



i am in germany, (just another working week in this beautiful country), and got a bunch of NOS rockers for the M30 engine, but despite being all of them same reference there are different colour marks on them, and the question is what does this mean ?

is this a similar case of the blue/red marks of the crankshaft bushings ? so are they really different ? or may i use these rockers alltogether ?

thanks

deQuincey,

Look just like the rocker arms I used last year in my rebuild. Febi I believe.
No name on them?
Don't have any wear marks so I can't help you with the paint marks.
Sometimes serious engine builders will buy dozens of rocker arms and weigh them and then class them together in groups. Just a thought.
I did blue print mine because rockers arms are probably the weakest part in any M30 engine.
There are a few (2) after market brands but not always available and very expensive.

 

[deQuincey]

deQuincey,

Look just like the rocker arms I used last year in my rebuild. Febi I believe.
No name on them?
Don't have any wear marks so I can't help you with the paint marks.
Sometimes serious engine builders will buy dozens of rocker arms and weigh them and then class them together in groups. Just a thought.
I did blue print mine because rockers arms are probably the weakest part in any M30 engine.
There are a few (2) after market brands but not always available and very expensive.

thank you for your comments,
these are bmw marked, no other mark visible
the paint as a weight reference makes sense to me, i am worried by the fact that the laterals that hold the eccentric wheel have those teeth, but not all,...

BTW, what does "blue print" mean ?

 

[m5bb]

thank you for your comments,
these are bmw marked, no other mark visible
the paint as a weight reference makes sense to me, i am worried by the fact that the laterals that hold the eccentric wheel have those teeth, but not all,...

BTW, what does "blue print" mean ?

Yes, I see that. Just a mix of arms that weren't all manufactured at the same time. Mine had the laterals but not anymore.

Blue printing is the process of going over an item and removing most all of the manufacturing marks and seams. Those places are usually where weak spots can develop and cause a rocker to crack or break.
The weakest spot is usually in the big curve under the adjustment cam.
I only did this on an engine that could see 6000-6500 revs.
For a street engine these stock arms will last 3-400000 miles with proper maintenance. I have a 533i with 312000 miles and it's never had the head off.

 

[Lotuss7]

Yep,

"Blue Prnting" is a still used but old school term...back when designs were hand drawn and printed for reproduction. The drawings were light and dark blue. Sure there was a similar Spanish term.

In this case it essentially means establishing the design criteria and specification for an engine build. Tolerances; weight, balancing; removal or polishing of extraneous material to reduce oil adhesion and lower friction; enlarging bearing channels for improve oil flow; porting, polishing, flowing heads; overbore; etc. etc.

Can be broad or narrow depending on the needs and budget. If someone says "my engine is balanced and blueprinted" there is a pretty large specturm as to what that might include.

 

[rsporsche]

Yep,

"Blue Prnting" is a still used but old school term...back when designs were hand drawn and printed for reproduction. The drawings were light and dark blue.

John,

you must not be old enough ... you are talking about blue line printing. Blue printing was a much different animal that you didn't do by putting the original + paper into a machine. it was a photographic process with a negative.

 

[Lotuss7]

John,

you must not be old enough ... you are talking about blue line printing. Blue printing was a much different animal that you didn't do by putting the original + paper into a machine. it was a photographic process with a negative.

Ha! Perhaps not!

And you are correct and I do remember, but although I was part of the ink on mylar days prints were as you say...blue line. Never a photographic process. But...local west coast lexicon still called them blueprints generically, although they could be had in black, blue or sepia tone. Miss the smell of ammonia!