Jump to content

rocker arm and valves differences


PatAllen
 Share

Recommended Posts

I remember there was an well detailed document in a old roundel magasine about rocker arm differences...cant find it...

How often is it to find surface cracks on the rubbing pad ? It looks like 75% of the one i have got surface cracks...

I can see 3 different types for sure...which one are the best ?

1-rough casting with grinded top portion

2-rough casting without grinded top portion

3-76' dated ones with textured surface

Also, i found that there is 2 type of the "larger" 46mm intake valve. There is a thick and a thin one.

On the picture, the thin one is on the left, the thick one in the middle and the right one is a tulip valve found on SOME very early 121 head which are 44mm, just to show one.

Any idea on that one ? the thin one flow better on my flow bench than the thick one, at low lift.

The thick one could benefit of a back-cut, the thin one doesnt have enough room for it, the contact surface is just wide enough.

post-119-13667639517425_thumb.jpg

post-119-13667639519509_thumb.jpg

Link to comment
Share on other sites

years ago, when i worked at dallas european, we had a batch of bad rocker arms. at that time, the aftermarket vendors were laso and febi. but i know that they used to buy from each other, because sometimes laso rockers were in febi boxes, and vice versa. i could take a rocker shaft, and string a bunch of rockers on them, and you could see them all out of line; like a bunch of drunk soldiers in formation(and i seen them, too). we had hundreds in stock, and hundreds were returned. so a couple days later, one of the companies(i forget which one, i think febi) sends these 2 reps over from germany. the owner calls me into the conference room, intro's me, and tells me to tell them the problem. i tell them that their rockers suck. they are all machined wrong, and i wont sell them. these germans call me a liar. i was pissed. so, i go out in the warehouse, and get a dozed rockers, and a shaft, string them all together, and show them. they turn to each other, and are speaking in german, then they tell me that, "ok, there are some bad ones, but it is only a small amount." yah, bull. so i tell them that we have 1500 in stock, AND THEY ARE ALL BAD. chew on THAT, sucker. so then they again converse with each other in german, then they ask, "ok, so how can we solve this?" i tell them that for me, they will have to warranty the part AND the labor. they refuse. we send them all back. from then on, i show the product manager, who was a complete dumbass, how to line up the rockers, and get samples before ordering. and then, when the batch comes in, check them, cause them germans are not playing with a full deck. while i was there, i had similar run ins with the mahle rep, ate, textar, and several others.

Link to comment
Share on other sites

years ago, when i worked at dallas european, we had a batch of bad rocker arms. at that time, the aftermarket vendors were laso and febi. but i know that they used to buy from each other, because sometimes laso rockers were in febi boxes, and vice versa. i could take a rocker shaft, and string a bunch of rockers on them, and you could see them all out of line; like a bunch of drunk soldiers in formation(and i seen them, too). we had hundreds in stock, and hundreds were returned. so a couple days later, one of the companies(i forget which one, i think febi) sends these 2 reps over from germany. the owner calls me into the conference room, intro's me, and tells me to tell them the problem. i tell them that their rockers suck. they are all machined wrong, and i wont sell them. these germans call me a liar. i was pissed. so, i go out in the warehouse, and get a dozed rockers, and a shaft, string them all together, and show them. they turn to each other, and are speaking in german, then they tell me that, "ok, there are some bad ones, but it is only a small amount." yah, bull. so i tell them that we have 1500 in stock, AND THEY ARE ALL BAD. chew on THAT, sucker. so then they again converse with each other in german, then they ask, "ok, so how can we solve this?" i tell them that for me, they will have to warranty the part AND the labor. they refuse. we send them all back. from then on, i show the product manager, who was a complete dumbass, how to line up the rockers, and get samples before ordering. and then, when the batch comes in, check them, cause them germans are not playing with a full deck. while i was there, i had similar run ins with the mahle rep, ate, textar, and several others.

i know what you mean, i can tell you they seems to be all oem rockers, none of them are febi. I didnt aligned them all on a shaft but i can tell you they all align up perfect.

I an not very concerned about this, but more about the shiney surface cracks.

I did try to break one that seemed to have more cracks than the others, to no avail, it was still super strong.

all the ones i am expecting to reuse can be aligned and the pads are within +-10 thou in between them, note that thoses had the pad surfaced (not by me).

post-119-13667639521745_thumb.jpg

post-119-13667639523594_thumb.jpg

Link to comment
Share on other sites

Guest Anonymous
The guys at Skidmark Racing in NC made a nice set of billet aluminum rocker arms.

Perry races a 2002 and has his M10 engine turning at 11k RPM.

Cheers!

Someone needs to post up some video of his 8v M10 spinning at 11,000 RPM, I would like to see that.....

www.alpinabmw2002.com

Link to comment
Share on other sites

...Someone needs to post up some video of his 8v M10 spinning at 11,000 RPM, I would like to see that.....

www.alpinabmw2002.com

So would I.

I didn't actually see it run, it was out of the car on a stand. But, he runs a custom grind Cam on new forged billet fed by twin 50 DCOEs. His lift and duration has to some kind of crazy!

Cheers!

Link to comment
Share on other sites

Today, you can get Febi and BMW rockers.

They are identical, except that the BMW rockers say BMW on them.

Both will have some chance of voids in them.

My personal theory is that they both come out of the same plant,

it's just the labels are different- so they change a plug in the casting.

The small cracks in the lash pads are new to me-

I HAVE seen 'peckering' where the cam plucks out small voids in the pad.

Delta says (and it makes sense) that that's a sign that the valve's floating.

The rocker gets off the cam and then when it smacks back down, sometimes

you get a pressure weld (at the microscopic level) to the cam.

Usually, they're just worn more or less out of the ideal curve.

I too like the 'shot peened' appearance rockers- I think that was the

best of the aluminum era rockers.

fwiw,

t

Link to comment
Share on other sites

Guest Anonymous
...Someone needs to post up some video of his 8v M10 spinning at 11,000 RPM, I would like to see that.....

www.alpinabmw2002.com

So would I.

I didn't actually see it run, it was out of the car on a stand. But, he runs a custom grind Cam on new forged billet fed by twin 50 DCOEs. His lift and duration has to some kind of crazy!

Cheers!

If this is true... gotta be honest.. can't imagine it lasting long.. maybe the ocasional over-rev to 11k and it not going to pieces but I don't see piston speed at 11k being feasable for a long stretch. Less he did a 1600 crank and big bore.

Link to comment
Share on other sites

I too like the 'shot peened' appearance rockers- I think that was the

best of the aluminum era rockers.

I've been hand-selecting BMW/Febi rockers and/or the IE Heavy Duty cast aluminum rockers, cleaning-up the casting marks and having them shot-peened. It's time consuming, value/longevity to be determined... (spinning no more than 8,000 rpms). -KB

Link to comment
Share on other sites

I think the most important thing is that the curvature of the rocker pads line up perfectly in sideview so that the valves experience the same acceleration and motion. (either as they did before when replacing all 8, or as each other if replacing singles)

But another consideration is the pad's length and position relative the rocker safts. For example, I think the IE HD rocker are a good value if they're any stronger than stock but I noticed that their pads are .050" or so closer to the rocker shaft than stock which allows their leading edges to nose into a Schrick 316's lobes at a harsh angle right around 50% lift.

Maybe its no big deal?, obviously they wouldn't have that issue on all cams, but tellyawhat this set is spankin new and for sale if anyone would like to try.

[/img]

post-119-13667639540757_thumb.jpg

post-119-13667639541871_thumb.jpg

Link to comment
Share on other sites

If this is true... gotta be honest.. can't imagine it lasting long.. maybe the ocasional over-rev to 11k and it not going to pieces but I don't see piston speed at 11k being feasable for a long stretch. Less he did a 1600 crank and big bore.

Well... remember it is a race engine. These have differing criteria as compared to a street engine. And longevity isn't especially one of them.

But, Perrry told me it is balanced to 0.1gm, and it's usually not the reciprocating gear which limits RPMs, it's the valvetrain and the ancillaries.

I have no doubt he runs at these RPMs. But, I have no idea how many hours or miles he gets between rebuilds. These things are less important for a race engine.

When I ran my formula ford open wheeler, I planned on certainly one rebuild each season, and possibly two. Economically crippling if it turned out to be three.

Cheers!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...