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Discussion Starter #1
Should the rocker arm roll across the top of the valve stem or should it stay in the center of the valve stem and be as norrow as possible?.
 

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steelcomp was here
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Should the rocker arm roll across the top of the valve stem or should it stay in the center of the valve stem and be as norrow as possible?.
The sweep should be as narrow as possible. Do a search, this subject has been discussed in depth here.
 

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www.highflowdynamics.com
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OH NO! miller's web site is gone! Anybody have that on a down load?
Jim Miller and I speak regularly, several times a week.

Miller is revising the website and business. Miller Engineering, or MEI, will become Miller Products Group, or MPG (already has), and the new website will ensue and of course will include all the important vavle train info.

For decades Jim has offered priceless information for free, and which is based on his extensive research and development on valve train systems and rocker arm geometry. The new website will advertise all the Miller products; the info portion of the website will be subscription-based.

LO
 

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steelcomp was here
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What's amazing to me is when you think about how critical cam design is in relation to degrees of cranksahft rotation, it's obvious how important it is to get the rocker geometry right. Being off on the PR lengths (under or over arcing the rocker) can cost many degrees of rotation of the crank. The cam is designed to open and close the valve in specific relation to these degrees of crank rotation. If your P/R length is off, then your rocker geometry is off, your cam is off, and if you have a custom grind, you might as well have thrown the $$ out the window 'cause it isn't doing what it's supposed to.
 

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Premium Member
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Jim Miller and I speak regularly, several times a week.

Miller is revising the website and business. Miller Engineering, or MEI, will become Miller Products Group, or MPG (already has), and the new website will ensue and of course will include all the important vavle train info.

For decades Jim has offered priceless information for free, and which is based on his extensive research and development on valve train systems and rocker arm geometry. The new website will advertise all the Miller products; the info portion of the website will be subscription-based.

LO
Paul, I was told he went to work for Randy at Harland Sharp.
 

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www.highflowdynamics.com
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Paul, I was told he went to work for Randy at Harland Sharp.
Wow Straub, you are really in the know ;) that was to remain top secret info for some time.

Not sure how much I can elaborate on this....yes, Miller Products Group (MPG) and Harland Sharp (HS) were in negotiations to combine forces. In short, I believe Mr. Sharp senior wants to pass the biz to his kids, and (if I got this right) his kids like the Mid-Lift technology and wanted to license it from MPG. I think that MPG was to license the technology and also Jim would come on as a consultant. HS was going to revise their rocker arm line with the technology; HS would remain an entity unto itself and sell its rockers; MPG would remain an entity unto itself and sell their rockers; and there might have even been the birth of a new line of new rocker arms (Miller-Sharp? :)bulb ). This may or may not come to fruition and although I cannot say for sure I now suspect now that MPG just might blaze their own path as will HS.

Chris, please call for any further details on this particular matter.

LO
 

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www.highflowdynamics.com
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1,161 Posts
... think about how critical cam design is in relation to degrees of cranksahft rotation... Being off on the PR lengths (under or over arcing the rocker) can cost many degrees of rotation of the crank (relative to valve position - LO). The cam is designed to open and close the valve in specific relation to these degrees of crank rotation (optimize timing events -LO) . If your P/R length is off, then your rocker geometry is off, your cam is off, and if you have a custom grind, you might as well have thrown the $$ out the window 'cause it isn't doing what it's supposed to.
This is absolutely 100% true. To give others an idea how critical timing events can truly be, consider this: Two camshaft manufactures may offer the same advertised profiles (peak lift/[email protected]/LSA), yet each of these cams can give notably different power numbers. Why? For one, the camshafts in question probably have differing ramp rates. Similar results can occur with poorly optimized valve train geometry: since rocker arms are radial devices that are transmitting linear information from the cam lobes to the valves, a poorly optimized valve train will have a direct effect on the information that is transferred. This is what 'comp is referring to when he uses the terms "over-arcing" and "under-arcing." Major loss of important info due to poor valve train setup

AND we haven't even bugun to talk about all the other issues that pop up with poor valve train optimzation, such as valve train harmonics, frictional losses, broken vavle train parts that would otherwise hold up to far greater abuse had they been properly set up in the first place, etc.

LO
 

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Premium Member
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Wow Straub, you are really in the know ;) that was to remain top secret info for some time.

Not sure how much I can elaborate on this....yes, Miller Products Group (MPG) and Harland Sharp (HS) were in negotiations to combine forces. In short, I believe Mr. Sharp senior wants to pass the biz to his kids, and (if I got this right) his kids like the Mid-Lift technology and wanted to license it from MPG. I think that MPG was to license the technology and also Jim would come on as a consultant. HS was going to revise their rocker arm line with the technology; HS would remain an entity unto itself and sell its rockers; MPG would remain an entity unto itself and sell their rockers; and there might have even been the birth of a new line of new rocker arms (Miller-Sharp? :)bulb ). This may or may not come to fruition and although I cannot say for sure I now suspect now that MPG just might blaze their own path as will HS.

Chris, please call for any further details on this particular matter.

LO
I try to keep an ear on what is happing. This industry is in for some rough times.
 

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steelcomp was here
Joined
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26,512 Posts
Wow Straub, you are really in the know ;) that was to remain top secret info for some time.

Not sure how much I can elaborate on this....yes, Miller Products Group (MPG) and Harland Sharp (HS) were in negotiations to combine forces. In short, I believe Mr. Sharp senior wants to pass the biz to his kids, and (if I got this right) his kids like the Mid-Lift technology and wanted to license it from MPG. I think that MPG was to license the technology and also Jim would come on as a consultant. HS was going to revise their rocker arm line with the technology; HS would remain an entity unto itself and sell its rockers; MPG would remain an entity unto itself and sell their rockers; and there might have even been the birth of a new line of new rocker arms (Miller-Sharp? :)bulb ). This may or may not come to fruition and although I cannot say for sure I now suspect now that MPG just might blaze their own path as will HS.

Chris, please call for any further details on this particular matter.
LO
LOL...I'm guessing you should call him...:D
 

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What's amazing to me is when you think about how critical cam design is in relation to degrees of cranksahft rotation, it's obvious how important it is to get the rocker geometry right. Being off on the PR lengths (under or over arcing the rocker) can cost many degrees of rotation of the crank. The cam is designed to open and close the valve in specific relation to these degrees of crank rotation. If your P/R length is off, then your rocker geometry is off, your cam is off, and if you have a custom grind, you might as well have thrown the $$ out the window 'cause it isn't doing what it's supposed to.
Okay now I'm really confused after this! So If I put longer or shorter PUSH-RODS in my motor, then I mess with duration? Rocker geometry has nothing to do with specs of the cam. It has to do with the contact point and efficiency of rocker to valve tip. I can't wiat for the come back on this! M
 
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