Mid lift rockers

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Re: Mid lift rockers

Postby Warp Speed » Fri Sep 01, 2017 9:13 am

What is Miller doing now?

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Re: Mid lift rockers

Postby nickpohlaandp » Fri Sep 01, 2017 12:15 pm

kimosabi wrote:Well saying that "it does not matter" depends too doesnt it....


Just had to tag you kimosabi. Reading through this thread is somewhat amusing to me. I am not one of the worlds greatest engine builders, nor have I ever claimed to be, but I will say it's nothing short of amusing when someone is advocating for their rocker arm and in the same breath stating that a portion of it has "nothing to do with geometry". I stay away from vendors like this who make such blatantly wrong statements.

If you ever dabble in the modular Ford engines you're bound to come across a company called MMR. They are the worst offender I've ever seen.
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Re: Mid lift rockers

Postby Paul Kane » Sat Sep 02, 2017 12:12 pm

Steve.k wrote:Im assuming he went with alloy 1.for cost and ease of construction 2 likely 80% of rocker sales are in this category and 3 his theory would offer as much strength to a alloy rocker as a conventional stainless or close. So it was his best option....I believe miller like most entrepreneurs started with alloy because of cost, and when your competing with companies like Comp,Jesel, crane and the likes its tough to get foot in door..:
Actually, pretty much everyone was making aluminum rocker arms back then 25 years ago, and many still do. I'm not sure where the idea of "cheap" comes in--MEI first came onto the scene as an exotic, high-end Shaft Rocker and Stand System manufacturer supplying drag race teams and Cup teams. (The commercial stud rocker lines were toward the end and that's probably why they weren't well known in the hot rod market.) They pioneered materials, engineering, and manufacturing practices not yet used in the rocker arm industry at the time. They certainly didn't compromise material quality for their aluminum recipe choices--their stud rockers (which MEI brought out later) were made of either 7075-T6 aluminum or 7150-T6 aluminum (depending on product line), both of which demonstrated the highest destructive testing measurements over any of the other aluminum stud rocker arm manufacturers of which I am aware. MEI also applied the exact same destructive testing and material analysis to their competitors' rocker arms as they did their own in-house product so as to get a scope of what was really going on in the industry and where they stood. I'm pretty sure their rocker bodies had the highest destruct levels of the stud rockers tested, and given the material they were using it shouldn't be surprising.
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Re: Mid lift rockers

Postby Paul Kane » Sat Sep 02, 2017 12:41 pm

Geoff2 wrote:Aluminium is NOT the best material for rocker arms, as there is no way to test it's finite fatigue limit, before it goes 'bang ' [ Unlike steel ]..
There is a whole lot more to rocker arm design and material selection than "best/strongest." Both alloys have their attributes for given applications. Good quality aluminum rocker atms should have a lifespan that will exceed most engines, or possibly several engines.

Based on your rationale of aliminum "finite faigue limit" relative to rocker arm application, we should all ditch our aluminum pistons before they break too, and our cast aluminum heads before we blow the chambers into the cooling jacket, etc.

I'm not knocking steel rocker arms, I'm saying there is no "best," and that "strongest" is not always the end-all when choosing an engine component's material make up. We've made both steel and aluminum rocker arms for our Hemi heads; both rockers have pluses and minuses.

(There is more steel/aluminum discussion earlier in this thread.)
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Re: Mid lift rockers

Postby Paul Kane » Sat Sep 02, 2017 12:59 pm

kimosabi wrote:I'm not talking about whether it makes a difference or not. Not one place have I stated that "it matters". I'm saying that geometry applies. Geometry is math. Math applies. .
That's been the point all along--that it "doesn't matter" relative to the Installation Geometry.

The statement you're questioning is to be read in the context of setup, or installation--we're all talking about rocker arm Installation Geometry in this thread now, this isn't even Mid-Lift specific.

To clarify for you: "Where the roller tip rides atop the valve stem has nothing to do with setting up your rocker arm geometry."

In other words, when setting up your valve train you should focus on optimizing the rocker arm's angular and radial orientation as it relates to it's neighboring valve train components, and just let the roller wheel fall wherever it may atop the valve stem...inboard, outboard, wherever.

Being unhappy with a roller wheel's physical position falls under the Design Geometry of the rocker arm, it is not an Installation Geometry issue with the setup. "Relocating" a roller wheel by way of changing your perfect pushrod length will almost always be at the expense of your Installed Geometry, since where the roller wheel sits atop a valve stem has nothing to do with the latter.
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Re: Mid lift rockers

Postby kimosabi » Sun Sep 03, 2017 1:21 am

nickpohlaandp wrote:
kimosabi wrote:Well saying that "it does not matter" depends too doesnt it....


Just had to tag you kimosabi. Reading through this thread is somewhat amusing to me. I am not one of the worlds greatest engine builders, nor have I ever claimed to be, but I will say it's nothing short of amusing when someone is advocating for their rocker arm and in the same breath stating that a portion of it has "nothing to do with geometry". I stay away from vendors like this who make such blatantly wrong statements.

If you ever dabble in the modular Ford engines you're bound to come across a company called MMR. They are the worst offender I've ever seen.


You should read the email conversation I had with this miller-self proclaimed God vendor after I asked one simple question, and after they approached me with their superduper "promotion".. Responses were salty to say the least. Just like Paul Kane now backpeddles and changes the terminology of used geometry to try to illustrate that he wasn't talking about geometry geometry, but geometry. LOL

Paul Kane, give it a rest man. I'm part of no choir.

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Re: Mid lift rockers

Postby Geoff2 » Sun Sep 03, 2017 5:04 am

Paul,

Any rocker that can be made out of alum can be made out of steel or S/S...& it will be stronger as well. Steel has an added advantage in that the metal fold under the fulcrum of a steel rocker does not need to be as thick as that of an alum rocker, because the steel is MUCH stronger. This allows for a larger fulcrum bearing, for better stability & longevity.

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Re: Mid lift rockers

Postby Paul Kane » Sun Sep 03, 2017 5:51 am

kimosabi wrote:You should read the email conversation I had with this miller-self proclaimed God vendor after I asked one simple question, and after they approached me with their superduper "promotion".. Responses were salty to say the least
You obviously remain pretty upset about the interaction you had with Mr Miller, as you've mentioned it in this thread before. Are you sure that experience hasn't affected your perspective or open mindedness in this discussion forum? Because it almost seems as though you are holding onto that and arguing rather than engaging in an open discussion here.

kimosabi wrote:...just like Paul Kane now backpeddles and changes the terminology of used geometry to try to illustrate that he wasn't talking about geometry geometry, but geometry. LOL
Nothing's changed in the terminology or in this discussion, as we're talking about installation geometry. The roller wheel can be located anywhere on the valve tip and the angle of attack between the rocker and the valve remains unchanged. The statement in the context of this discussion remains:

"Where the roller wheel rests atop the valve stem has nothing to do with geometry."

I changed nothing in that regard. I only offered to kindly, further spell it out so that you might understand. You're talking about a rocker arm design change--you cannot "change" the design of a rocker arm by altering its installed geometry, as you'll be altering the installed geometry.

Incidentally, amidst all this back-and-forth debating, you've yet to offer any explanation or description as to why you feel that the opposite is true, that "the roller tip position affects geometry." Can you?

kimosabi wrote:Paul Kane, give it a rest man. I'm part of no choir.

Heh, obviously. :) You're welcome to subscribe to whichever geometry theory you want. Just know that those practices to which you seem to subscribe will trick your engine into thinking it has a smaller cam, with differing timing events, and a less stable valve train, and might even convince you that you need more valve spring than is actually necessary.
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Re: Mid lift rockers

Postby Paul Kane » Sun Sep 03, 2017 6:23 am

Geoff2 wrote:Paul,

Any rocker that can be made out of alum can be made out of steel or S/S...& it will be stronger as well.
For the most part, yes. I already said that in my last post to you (where I mentioned we've made the same rocker arms in both steel and aluminum). But that doesn't make the steel rocker the automatic best choice--there is a whole lot more to consider than strength. Sometimes you need more strength, but other times you may have adequate strength but want less mass moment of inertia, for example.

Geoff2 wrote:Steel has an added advantage in that the metal fold under the fulcrum of a steel rocker does not need to be as thick as that of an alum rocker, because the steel is MUCH stronger. This allows for a larger fulcrum bearing, for better stability & longevity.
That's a good example if you need a larger bearing while maintaining rocker body profile. And there's not much downside to the use of steel in that area of the rocker body either. But there may be downsides to the use of steel elsewhere in the rocker body design, one of which I touched on directly above in this post. Again, which alloy one chooses will matter depending on the rocker arms shape, overall design needs, engine application/usage, peak rpm, etc etc etc.

You can point to steel's strength over aluminum all day long and I won't disagree. My point is that material of the greatest strength alone is not what makes a good rocker arm, nor does it guarantee the rocker will perform in the application as needed, nor even guarantee it's not prone to failure. Sometimes a material other than stainless steel is better suited, it depends on a multitude of considerations.
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Re: Mid lift rockers

Postby kimosabi » Sun Sep 03, 2017 8:19 am

"Incidentally, amidst all this back-and-forth debating, you've yet to offer any explanation or description as to why you feel that the opposite is true, that "the roller tip position affects geometry." Can you?"

Paul Kane, If the rocker is rotated a little sideways on the stud ALTERING THE ROLLER TIP POSITION, to clear pushrods or w/e, then it definitely affects setup rocker geometry and you are definitely losing cam info to the valve. I'll expand on that and say that , when you do that you tilt the pushrod = lose information to the valve. That's geometry. So how long are you gonna defend your position that "where the rocker tip rests on the valvetip, have nothing to do with geometry". This is not even design geometry, that's installation geometry. You have to be clear when making blunt statements like that. Well it was clear but it was wrong.

"You obviously remain pretty upset about the interaction you had with Mr Miller"

Just another one of your assumptions.

It's easy to see that the common off the shelf rocker is wrong spec for many applications. That's why I had mine custom ordered, and a whole lot of other builders do too. Show me a dyno comparison between the Miller rockers and an off the shelf roller rocker. The miller rockers also struggle with a bad rep when it comes to quality. That is hard to get away from.

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Re: Mid lift rockers

Postby Paul Kane » Sun Sep 03, 2017 10:15 am

kimosabi wrote:Paul Kane, If the rocker is rotated a little sideways on the stud ALTERING THE ROLLER TIP POSITION, to clear pushrods or w/e, then it definitely affects setup rocker geometry and you are definitely losing cam info to the valve. I'll expand on that and say that , when you do that you tilt the pushrod = lose information to the valve. That's installation geometry.
kim, you are now arguing how the roller wheel is positioned atop the valve, not where the roller wheel is positioned atop the valve. In the world of valve train geometry there's a huge difference between the two, and "how" the wheel is positioned is certainly not what's being discussed here.

But ironically enough, I can now use your example and hopefully you'll finally understand what I've been saying.

Per your example, let's put the roller wheel on its edge. In other words, only the edge of the roller wheel's radius touches the tip of the valve stem, and now the rocker arm's radial articulation imposes glancing forces over the valve stem. Is the geometry affected than if the roller wheel's radius were seated flat on the stem tip? Yes, of course, That's obvious enough. But it's not what I'm talking about.

So now, let's incorporate what Im talking about to your own example:

With the roller wheel on it's edge as per your description, does the geometry change relative to where that angled roller wheel rests atop the valve? Nope. Not one bit. The roller wheel can be angled atop the valve stem and sitting on its edge just as you describe, but regardless of whether the roller wheel is centered on the tip of the valve, or is inboard, or is outboard, or even to the left or to the right, the angle of attack between the two components (rocker arm & valve) remains unchanged.

This is because "where the roller tip rests atop the valve has nothing to do with geometry." It can be positioned anywhere atop the valve stem and the geometry is unaffected.


kimosabi wrote:It's easy to see that the common off the shelf rocker is wrong spec for many applications. That's why I had mine custom ordered, and a whole lot of other builders do too.
That's certainly one reason why MEI produced rocker arms intended for specific engines--no need to approach a rocker arm manufacturer and have them make a single set of custom, geometrically correct rocker arms for you (unless there are other specific features that you need for your setup...but any rocker arm manufacturer can do that.)


kimosabi wrote:Show me a dyno comparison between the Miller rockers and an off the shelf roller rocker
I'm not sure what your point is about dyno tests and horsepower with or without Miller rockers. Miller rocker arms were never promoted as a magic horsepower adder. They offer optimized valve train geometry per the Mid-Lift Standard, pure and simple. Any brand rocker arm utilizing Mid-Lift design geometry offers the most efficient transfer of camshaft information to the valve. All the ancillary gains (reduced wear, reduce harmonics, improved valve train stability, etc) are side benefits, not the goal. So one ought not buy Mid-Lift rockers thinking they'll make more horsepower; they are used to optimize valve train geometry. Under the practice of the Mid-Lift Standard, camshaft changes should be made at the cam, not utilize the rocker arm as a second dynamic to the cam (which a lot of engine builders inadvertently do, often during dyno testing).

Whew, hope this helps this time around. I do understand what you're saying, but I'm not sure how else to describe to you what I'm saying.
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Re: Mid lift rockers

Postby Warp Speed » Sun Sep 03, 2017 10:45 am

I'd like to know what instance an aluminum rocker has an advantage over steel other than ease of manufacturing?!?

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Re: Mid lift rockers

Postby Paul Kane » Sun Sep 03, 2017 11:07 am

Warp Speed wrote:What is Miller doing now?
I lost touch with Mr. Miller a few years ago and can't say for sure what he's up to today. And while I'm not at liberty to disclose that which were his other interests and pursuits at the time, I will say that I found them all interesting.

Warp Speed wrote:I'd like to know what instance an aluminum rocker has an advantage over steel other than ease of manufacturing?!?
At this day and age I don't know that manufacturing rocker arms is outlandishly easier in aluminum than steel. But as far as attributes of steel vs aluminum in general, off the top of my head mass moment of inertia may be better with certain designs in aluminum over steel. Aluminum also dissipates heat much faster than steel (it absorbs heat faster and disipates it faster).

"Alum vs steel alloys for rocker arms" might be a good thread topic to start unto itself. Hopefully a large number of rocker arm manufacturers could engage rather than just spit-balling presumptions.
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Re: Mid lift rockers

Postby Warp Speed » Sun Sep 03, 2017 12:18 pm

Paul Kane wrote:
"Alum vs steel alloys for rocker arms" might be a good thread topic to start unto itself. Hopefully a large number of rocker arm manufacturers could engage rather than just spit-balling presumptions.


That would be a short thread with people of any good sense! LOL

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Re: Mid lift rockers

Postby engineguyBill » Sun Sep 03, 2017 3:36 pm

Warp Speed wrote:What is Miller doing now?



I don't know . . . . . . . Maybe someone who knows for sure will enlighten us.
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