HD rocker arms ....lesson learned

[zaq123]

So what is a consensus as it sits today? Are OEM rocker arms actually Febi ones? Any advantage going OEM or it's the waste?

[TobyB]

Also stiffer springs were used.

The numbers here matter- quite a bit. Nose and seat pressures vary tremendously on 'stiffer' springs,
and I learned (also the hard way) that you really have to do your own measurements and maths.

Febi has been making the OEM single cam rockers for decades- they just have 2 moulds for the castings.
They use the same process, and create the same voids. For racing, I would buy 20 Febis,
pick out everything with no visible external voids, and start polishing the undersides.
If I broke through to a void, I'd set that one aside, too. I usually got a set of 14 to 16 of them.
I ran the 'voidy' ones on street cars with no problems.

I also found that it was worth bluing the cam and using soft springs to make sure the geometry was
correct. Like you, I'd sometimes find that the pad wasn't contacting the cam well at all. That was when
I gave up on the currently- available HD rockers and stayed with Febi- their pad alignment was usually pretty
good, and when it was off, it was easy to correct with a very mild resurface.
I very much regret tossing my bucket of used rockers when we moved shop- resurfacing rockers isn't difficult
if you make a pretty simple fixture....

Likewise, I have broken in cams on soft springs, and then put the higher pressure springs in after a test day or 2.
It's not as much fun running around with a 6k rev limit, but there's still a lot of things you can work on, if you take
the effort to regear for it.

t

[hasa]

Questions for everyone struggling with rockers:

1) Do you measure your valve spring stiffness (installed height & max lift). This is crucial for preventing valve float which destroys everything in valvetrain. N/A M20 street / race engine requires 120kg at max lift with Febi/BMW rockers and typical race cam.

2) Do you use oil that has additives for old-fashioned valvetrain, high ZDDP content?

I haven't broken yet any rockers or worn out a cam lobe. Silly 312 degree cam, 7500 rev limit. Knock on wood.

[digger]

So what is a consensus as it sits today? Are OEM rocker arms actually Febi ones? Any advantage going OEM or it's the waste?

i got a response from MM and they dont sell the peened and inspected rockers anymore. They use a single coil spring with light nose "pressure"

[Northern]

No shortage of options at least...
Stock/Febi/HD crapshoot
Catcams steel (elephant foot/screw adjust)
KM cams steel (eccentric adjust)
VAC aluminum (elephant foot/screw adjust)
RHD roller (complete setup)...

Heard of issues with pad/cam wear with basically all options. Pick one and roll the dice.
Everything is made like shit these days.

[Panici]

Everything is made like shit these days.

Ain't that the truth.
Hard to find car parts that last, even from previously reputable manufacturers.

[digger]

Questions for everyone struggling with rockers:

1) Do you measure your valve spring stiffness (installed height & max lift). This is crucial for preventing valve float which destroys everything in valvetrain. N/A M20 street / race engine requires 120kg at max lift with Febi/BMW rockers and typical race cam.

2) Do you use oil that has additives for old-fashioned valvetrain, high ZDDP content?

I haven't broken yet any rockers or worn out a cam lobe. Silly 312 degree cam, 7500 rev limit. Knock on wood.

I had my OE valvetrain measured and setup. The head guy wasn't that happy with the spring forces with Schrick valve springs for 11.75mm lift so we went a bit higher (95-100kg iirc) and at the time VAC were selling some Eibach valve springs that fit nicely (i should have recorded the details as now VAC sell different springs).

You don't need anywhere near 120 kg for a true street cam engine with 7000 rpm that most people are concerned with, many have run a schrick on stocks springs without issue and catcams recommend 83kg for a typical street cam 11.5 mm lift basically what the schrick springs provide and whatever acceleration rates they use which are slightly higher than schrick

There is nothing unique about the m20 valvetrain system, any engine where the cam slides e.g., cam on bucket, flat tappet pushrod, finger follower (i.e. anything that isnt a bushed or needle roller) faces similar challenges doesnt matter if it is hydraulic or solid and yet they still work on modern oils.
You dont need high zddp (excluding say breakin)you need the right amount and need to be careful of other additives that reduce the effectiveness of the zddp e.g. high calcium is a problem as it depletes zddp it also promotes low speed preigntion so modern oils dont have as much zinc but they have less calcium and use other additive for wear protection so lets not stick to 1990's thinking