Steve.k wrote:Anyone ever try the mid lift 1.80 rockers. Have new set in box was going to try.
We were the west cost distributor for Miller Rockers for about ten years. I still continue to believe they are by far the best stud rocker arms for their intended application (raw materials, design geometry, installed geometry, etc).
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Steve.k wrote:...does he still make them and or does anyone else use his therory?
Miller's website is been transitioning from rocker arm sales to that of an educational one. He may have some remaining inventory of some part numbers, but most are long gone. We purchased the very last of his Big Block rockers (the 1.80 BB rockers that you have) and sold them off years ago. It's anybody's guess whether he'll opt to go back into production or not. As far as whether or not any other manufacturer's making Mid-lift rocker arms: Yes, some do quietly, and some do with alternate names that are obviously Mid-lift side-stepping trademark names.
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Steve.k wrote:...Going on Trackboss Cleveland number one.
Even though they will bolt to the Cleveland head, the Miller 1.80 ratio BB rocker arms are technically not Mid-Lift for the Cleveland engine. Ford themselves produced a singular rocker arm for the Big Block 385 Series and the Cleveland Series engines, however those two engines require a total of four different rocker arm designs between them in order to make up a set of Mid-Lift rockers for a Clevelend and a set of Mid-Lift rockers for a 385. The Miller BB 1.80 rockers will open and close the valves as good as any other rocker arm, and probably prove to be the strongest aluminum rocker bodies for your engine. But they are not Mid-Lift for your Cleveland engine.
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midnightbluS10 wrote:He still has a few rockers and has some of them on sale right now.....
This email is the ONLY LINK you will have to the special discount pages for both the PVS PA30 SERIES 3/4" diameter Miller gun-drilled trunnion STUD mounted rockers, in 1.60, or 1.70 Ratio, AND .150" RIGHT OFFSET pushrod cups for "N" Head, or Twisted Wedge.
Important Correction: The 0.150" Offset rockers are for the N351 heads and the Z304 heads, not the Twisted Wedge head as noted in the advertisement above.
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Steve.k wrote:I thought Jim originally worked with crane?I was wondering why no one wanted to use his theory or maybe they thought it drive cost of product up for sale purposes.
Jim Miller has worked and consulted with literally countless major rocker arm manufacturers, professional drag race teams, professional cup car teams, etc, than any career other rocker arm professional of which I am aware.
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kimosabi wrote:The so called "mid lift" concept they brag about is simply geometry rules applied to a pivot motion valve actuation. They didn't invent that, they built a rocker which you can custom order yourself. They don't own the rules but they market themselves as they would indeed own and invent geometry itself. I usually stay away from companies that include bashing other companies in their marketing.
You, sir, do not understand the Mid-Lift Standard or its intentions. but please don't feel singled out--most people misunderstand it.
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kimosabi wrote:Most rockers are too long to achieve minimal sweep and still be inside 1/3 of the valvetip.
Where the roller tip rests (or sweeps) atop the valve stem has nothing to do with valve train geometry. Also, there is a lot more to Mid-Lift than just applying the much-paraded "minimal sweep" theory.
kimosabi wrote:There's no way you can get rid of push rod arc but you can minimize it with proper geometry.
This is exactly what Mid-Lift does is "minimize" over-arcing on the pushrod side of the rocker arm...far more so than most other brands. in fact, this is the side of the rocker arm where the majority of (READ:
all kinds of) geometry (and trigonometry) is taking place.
kimosabi wrote:Yes it is a blanket statement because geometry is geometry. Rules are the same no matter what it says on the box sticker. Miller builds a rocker with different spec.
Mathematical geometry is mathematical geometry indeed, however there are many rocker arm geometry theories and geometry designs--that's the problem and that's what Mid-Lift addresses by establishing a Standard based on engineering efficiency. (It perplexes me that people keep missing this point.) Miller rocker bodies designed to have the greatest geometric efficiency for their intended engine application.
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MadBill wrote:According to this....Quick-Lift's® trick is not to maintain a constant ratio throughout as results from the Miller design, but rather to come off the seat at a higher ratio, drop back to nominal at mid lift, then close at the higher ratio.
And what an unwise idea that is...do you really want your valves to SLAM! against the seat on its way back to rest against the seat? Whew, talk about seat wear, guide wear, valve spring harmonics, etc! The nice thing about a Mid-lift rocker arm is that--unlike other rocker designs--the Mid-Lift rocker maintains its ratio as it travels thought its radial sweep better than any other non-Mid-lift rocker arm. Again, the Mid-Lift design is about engineering efficiency.
Harvey Crane himself once said to a close personal friend of mine (and his), "I wanted to build a better rocker arm, and Miller beat me to it!"
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stealth wrote:http://www.jesel.com/valvetrain/index.php/tech-tips-faq
ROCKER GEOMETRY
Rocker geometry is a function of the arc generated from the rocker arm and the relationship of the valve tip to rocker shaft height. Using this arc correctly is the difference between a smooth operating valvetrain and a valvetrain of worn out parts. Jesel’s Low Pivot geometry utlizes the portion of the arc that produces a minimal sweep pattern from half to full lift, a point at which spring pressures are exponentionally increasing. These added spring forces transferred against the nose roller have the potential to cause the roller to skid instead of roll across the tip bending the valve stem and wearing the guides. By minimizing the roller travel distance under high spring loads, the potential of roller skidding is reduced and valve guide wear decreased tremendously. As illustrated below, the Jesel Low Pivot geometry yielded almost .020” less roller travel during the critical stages of lift compared to a rocker set up for a symmetrical half-lift geometry.
All I can tell you is that when cup teams can spend MILLIONS on R&D and CHOOSE to use one particular type of geometry it makes sense to pay attention. Jesel seems to have a very good argument for not using Mid-lift geometry, but again I look to those with the resources to test every conceivable variation for both power and longevity.
1) Jesel's approach to valve train geometry is a different one, not necessarily the most efficient and certainly not a standard by which other theories may be measured.
2) Jesel's geometry is not the most efficient method of translating camshaft information to the valve.
3) Of course the roller tip skids! The primary purpose of the roller tip is
not to "roll" and/or "reduce friction," and it astonishes me that Jesel (or whomever wrote that article) doesn't get this.
4) Cup Teams do not use Jesel rockers nor do they use Jesel theory. They
used to use Jesel rocker arms. Then, they used to use Jesel rocker arm
and convert them to Mid-Lift. They also used Miller Mid-Lift rockers, a lot of teams did. And Jim consulted with other teams yet. Today, Cup Car teams mostly create their rockers in house and behind closed doors.
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