Choice of aftermarket cam rockers

[Litle brother]

I have gotten some very small pitting on one of my rocker arms. The area where the pitting occurs are typically where the cam touches the rockers at max lift.

To remedy this I am thinking of buying new aftermarket racing rockers.

So I have been looking at a couple of brands. First the forged DLC rocker arms from Schrick and then the billet tool steel DLC rocker arms from Pauter.

I would be very happy for input from you guys in here on what to choose

Regards
Eskild


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[Julius911]

Hi Eskild.

i am working with some few sets in titanium if its intresting? i think price will be almost same as rocker arms from pauter ( Porsche Rockers - Pauter) but this will be a lot better in titanium

best regards

[VFR750]

Web Cam weld hardfaces used rockers.

So that is an option.

[993Speedster]

Careful in your search for the "hardest/toughest" rockers or material available. I think there is something to be said for the cam being stronger than the rockers. If either of them had to be the "consumable" part in this equation, I think the rockers would be much easier to add into service inspection and replacement than camshafts. Just food for thought...

[Litle brother]

Thanks for all answers guys

[Litle brother]

Originally Posted by Julius911

Hi Eskild.

i am working with some few sets in titanium if its intresting? i think price will be almost same as rocker arms from pauter ( Porsche Rockers - Pauter) but this will be a lot better in titanium

best regards

Interesting, do you have some more facts, pics, etc ?

[Litle brother]

Originally Posted by VFR750

Web Cam weld hardfaces used rockers.

So that is an option.

Thanks, I have looked at that possibility also

[Litle brother]

Originally Posted by 993Speedster

Careful in your search for the "hardest/toughest" rockers or material available. I think there is something to be said for the cam being stronger than the rockers. If either of them had to be the "consumable" part in this equation, I think the rockers would be much easier to add into service inspection and replacement than camshafts. Just food for thought...

Yes, thats real good food for thought

[stownsen914]

Keep in mind that unless you are revving over 8500 RPM that cast rockers are a failsafe for 911 engines. For example, if you overrev, you might bend a valve and maybe break a rocker if you overrev it badly enough. If you have forged rockers, if you overrev there is no weak link anymore, which can mean lots more damage ...

[stownsen914]

Originally Posted by 993Speedster

Careful in your search for the "hardest/toughest" rockers or material available. I think there is something to be said for the cam being stronger than the rockers. If either of them had to be the "consumable" part in this equation, I think the rockers would be much easier to add into service inspection and replacement than camshafts. Just food for thought...

Good point.

OP - what springs are you using? I've seen some opinions expressed that some of the racing springs out there are really too stiff for our engines and cause unnecessary wear. I wonder if you are seeing that. Might be worth making sure you are solving the right problem here ...

[Litle brother]

Originally Posted by stownsen914

Good point.



OP - what springs are you using? I've seen some opinions expressed that some of the racing springs out there are really too stiff for our engines and cause unnecessary wear. I wonder if you are seeing that. Might be worth making sure you are solving the right problem here ...

Yes I have also been thinking about my valvesprings might be something to consider again.
They are from AASCO and are recommended, as I have been told, for my kind of enginebuild.
I don't think they are that much stiffer than the original ones that they should be harmful for either original rockers or titanium retainers.

[cgarr]

Are only the intakes pitting?

[Litle brother]

Originally Posted by cgarr

Are only the intakes pitting?

I have not taken more than this one out and it’s on the exhaust side.


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[cgarr]

exhaust get the most oil at least to the bushings: Pull a spring and measure the bind, and cam lift see if you have proper safety margin.

['76 911S 3.0]

Originally Posted by stownsen914

Keep in mind that unless you are revving over 8500 RPM that cast rockers are a failsafe for 911 engines. For example, if you overrev, you might bend a valve and maybe break a rocker if you overrev it badly enough. If you have forged rockers, if you overrev there is no weak link anymore, which can mean lots more damage ...

I can attest to this fail safe mechanism, I experienced an 8800 rpm over rev recently and broke a rocker. Saved the pistons from severe damage.

[Neil Harvey]

Please do not fit cast rockers in the event you over rev your engine the rocker becomes the "fuse". Fit the best rocker available for your application. Don't over rev your engine.

Spring pressures have to be calculated not assumed. The valve train part weights and the engine use are the most important factors here. All too often the spring pressures are far too high. Not just because of the elevated wear rate, but also the engine has to turn against this force.

From the photo, it does not look like it was an oil starvation issue, but you should check the oil tubes. It does not appear there was any heat involved. It is hard to see exactly and the cam lobe may tell another story.

Welded cam lobes if not done correctly will often cause issues as the lobe becomes the hardest part. Welding should only be done in the most special cases only. Unfortunately it is done often with unsuspecting results.

All steels have inclusions when manufactured. Cast probably has the highest level of inclusions.

Any inclusions under the surface will show up at sometime as the material above them will break down and the pits appear. Regrinding should be done with absolute care as the geometry can change. You can hard chrome the faces and grind back using the original radius point of origin. Care needs to be used when selecting who to do this work. We have had this done for years and have had zero failures.

[Spenny_b]

With absolutely no experience or technical knowledge on the subject of rockers and spring pressures, the only thing I would offer is that having spent some time with Brian Pauter when he popped in to see us on the Turbokraft stand at Rennsport Reunion, he seemed a genuinely lovely guy. Very approachable, straight up and easy to chat to. I know Chris works with him a lot as well, so if it were me going shopping, Brian/Chris would be my first phonecall.

[TimT]

Dopke used to refinish/make some nice rockers... doubt there are any available now.. he passed 11? years ago?