Rockers, which one's are better?

[rylee]

Guys;

Rebuilt a B34 head with all the guts from a b35 - It's sitting on the bench collecting dust on the baggie... Then I bought a used M90, so I took it apart, then pressure washed the hell out of it, and all the other parts from the motor. So I noticed these gleaming rockers:



Then I looked forlornly at the ones from the B35 already on the rebuilt head:



Are these made of something better, or just a hand built kinda thing...both do show a ridge from casting, however, the casting marks on the m90 rockers is mostly ground off...The design is different...This M90 came off a euro '79 635...

[rylee]

dang - I only now have come to realize that the pictures are reversed... OOps..Anyone know anything about the rockers in the second pictue? Any help would be great....

[Mike W.]

I've seen/used some like that before. I just go with the ones with the least wear in the bushing. In a stock engine, rockers aren't normally a problem. With a big cam and/or lots of revs, they can fail. I've heard the biggest thing is to smooth them so the load is distributed more evenly than something with a notch in it.

[George]

They most certainly fail in high rev situations. Take an M30/90 to 7k+ routinely and they snap in half. Helped pull a head last summer on an M90 that broke one in half after a mis-shift.


This is what I'm using on the turbo car:

IE Heavy Duty Shot Peened






When I get the time to rebuild the motor, this is what I'd like to go to:

Billet

[rylee]

Wow - those IE ones look way better than the stock ones I used for the rebuilt head...Apparently the M90 ones - while they look 'special' really aren't.. Man, that billet one Rocks! javascript:emoticon(':rockon:')Debating whether to take that head apart agin, and get serious with it...Detonating the head from some mishap is precicely what I'd like to avoid..Was looking at Paul B.'s turbo grind, wondering how much better than the b35 cam that would be - sixerkid, where do those billet ones come from if you don't mind me asking?

[George]

Wow - those IE ones look way better than the stock ones I used for the rebuilt head...Apparently the M90 ones - while they look 'special' really aren't.. Man, that billet one Rocks! javascript:emoticon(':rockon:')Debating whether to take that head apart agin, and get serious with it...Detonating the head from some mishap is precicely what I'd like to avoid..Was looking at Paul B.'s turbo grind, wondering how much better than the b35 cam that would be - sixerkid, where do those billet ones come from if you don't mind me asking?

Both come from IE.

[Mike W.]

In a stock engine, rockers aren't normally a problem. With a big cam and/or lots of revs, they can fail.

Like I said, with lots of revs they can fail. I've only had 2 M10/M30s (same rockers) over 7K, but neither had a problem. On E28's it's pretty much a moot point with the rev limiter built into the motronic. As a matter of fact, US spec E12's had one starting in 79, making it impossible to go over ~6400. Not that some of the people here aren't doing some interesting things, but ultra high revs seem to be a rarity.

[SamSpade]

\When I get the time to rebuild the motor, this is what I'd like to go to:

Billet

Wow, $85 each ($1,020 for 12). I won't need them but I love it when vendors go out of their way to design and manufacture serious stuff for these engines.

[Brad D.]

Man, those billet jobs are impressive.

[wkohler]

Well, thankfully, there are a few parts in common with the M10.

[rylee]

Dang. those are xpensive...Wonder if they're lighter than the original too? - are those billet rockers from IE aluminum? I can imagine it now........I become somehow independantly weathly.....I then buy these rockers, those dual springs with the titanium seats, then Pauls turbo grind............Then - then a S38B38 Crank an a an a

ah - oh, sorry - was daydreaming......javascript:emoticon('')
javascript:emoticon(':|')

[George]

Dang. those are xpensive...Wonder if they're lighter than the original too? - are those billet rockers from IE aluminum? I can imagine it now........I become somehow independantly weathly.....I then buy these rockers, those dual springs with the titanium seats, then Pauls turbo grind............Then - then a S38B38 Crank an a an a

ah - oh, sorry - was daydreaming

Yes Rockers are aluminum.

You're describing 1 or my 3 current builds.

I'm in the process of (slowly) building a high-rev turbo M30'd... in addition to a turbo s38.... in addition to a blown M30.

The s38 is running me dry. The exhaust manifold flanges alone are over $500!

The getrag 280/6 was over $4,000

So many ideas, so little time.


Nothing to do with wealth, everything to do with priorities.

[wkohler]

These rocker arms are CNC machined from 7075 aircraft quality aluminum. The material alone is about 3 times as strong as the cast factory rockers plus we've added material to the valve end to strengthen it even more. We've designed these with a swivel type adjuster for easy adjustment and less friction. It's well known that the rocker arms are the weak link in the M10 engine. If you race a BMW with a M10 engine you have probably already broken a rocker arm. These are not cheap but neither are broken rockers. Priced each. Picture shows our new design billet rockers to be available in late January 2007

[George]

These rocker arms are CNC machined from 7075 aircraft quality aluminum. The material alone is about 3 times as strong as the cast factory rockers plus we've added material to the valve end to strengthen it even more. We've designed these with a swivel type adjuster for easy adjustment and less friction. It's well known that the rocker arms are the weak link in the M10 engine. If you race a BMW with a M10 engine you have probably already broken a rocker arm. These are not cheap but neither are broken rockers. Priced each. Picture shows our new design billet rockers to be available in late January 2007

I fucking love 7075 AL.

If I had a choice I'd make almost everything out of that.

The beer I'm drinking right now should be in a bottle thats made from 7075. Its that awesome.

[wkohler]

My posts are made of 7075 AL.

[tsmall07]

You can break a rocker in an M30 at 6000rpm. I shift at 6000 when I'm on the track and broke one. I've heard the stock rockers are fairly weak and all replacements (stock) were redesigned to be stronger.

[FirstFives Dictator]

In a stock engine, rockers aren't normally a problem. With a big cam and/or lots of revs, they can fail.

Like I said, with lots of revs they can fail. I've only had 2 M10/M30s (same rockers) over 7K, but neither had a problem. On E28's it's pretty much a moot point with the rev limiter built into the motronic. As a matter of fact, US spec E12's had one starting in 79, making it impossible to go over ~6400. Not that some of the people here aren't doing some interesting things, but ultra high revs seem to be a rarity.

At SCCA Solo Nationals, 2 M20 cars I that tuned bumped rev limits of over 7200 rpm on the ProSolocourse and West Solo II course. Both cars had low mileage factory rocker arms. One car had broken an aftermarket arm a couple of years ago at ~ 7000 rpm (Motronic with chip)

The west course was fast and a little scary...