Mid lift rockers

General engine tech -- Drag Racing to Circle Track

Moderator: Team

User avatar
MadBill
Guru
Guru
Posts: 12628
Joined: Tue Nov 15, 2005 10:41 am
Location: The Great White North

Re: Mid lift rockers

Post by MadBill » Thu Aug 24, 2017 10:19 pm

Since the Mid Lift site says the last patents were granted in 2000 they should be expired by now, but I haven't seen any other rocker manufacturers trumpeting the concept.
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

kimosabi
Member
Member
Posts: 144
Joined: Sat Feb 22, 2014 5:01 pm

Re: Mid lift rockers

Post by kimosabi » Fri Aug 25, 2017 4:09 am

I encourage anyone to challenge them with a few questions when Jim Miller send those "promotions". I did and it didn't turn out well, as Miller seem to think he invented geometry. I simply asked them if the rockers were a set back trunnion and the shitstorm that ensued was hilarious. When I told them I have my own custom rockers, the poorly camouflaged patronizing that followed was pathetic.

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.

User avatar
MadBill
Guru
Guru
Posts: 12628
Joined: Tue Nov 15, 2005 10:41 am
Location: The Great White North

Re: Mid lift rockers

Post by MadBill » Fri Aug 25, 2017 9:18 am

Selden patented the motorcar in the late eighteen hundreds. Fortunately for everyone, it didn't hold up... http://www.autonews.com/article/2003061 ... o-industry
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

Schurkey
Guru
Guru
Posts: 1135
Joined: Sun Mar 01, 2009 2:42 am

Re: Mid lift rockers

Post by Schurkey » Fri Aug 25, 2017 12:39 pm

Perhaps I'm misinformed.

MILLER is big on MID-LIFT geometry.

CRANE was big on QUICK-LIFT geometry.
http://www.hotrod.com/articles/ctrp-060 ... cker-arms/

There used to be a Crane Cams animation of the rocker motion, but I can't find it anymore.

treyrags
Pro
Pro
Posts: 294
Joined: Thu Mar 25, 2010 5:33 pm
Location: Central Texas

Re: Mid lift rockers

Post by treyrags » Fri Aug 25, 2017 4:33 pm

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.
Kind of a blanket statement . From what I've seen they build their rockers specific to each application and they are mid lift correct on BOTH sides of the trunion, not just the valve side. I mocked up a set on a small block Ford in line head and when the valve side was correct the push rod side was correct also. The net lift was dead on throughout the lift with full spring pressure as well. That is virtually impossible to find with most rockers
Image

Steve.k
Pro
Pro
Posts: 333
Joined: Sat May 28, 2016 10:41 am

Re: Mid lift rockers

Post by Steve.k » Fri Aug 25, 2017 4:38 pm

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.

kimosabi
Member
Member
Posts: 144
Joined: Sat Feb 22, 2014 5:01 pm

Re: Mid lift rockers

Post by kimosabi » Sat Aug 26, 2017 12:42 am

treyrags wrote:
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.
Kind of a blanket statement . From what I've seen they build their rockers specific to each application and they are mid lift correct on BOTH sides of the trunion, not just the valve side. I mocked up a set on a small block Ford in line head and when the valve side was correct the push rod side was correct also. The net lift was dead on throughout the lift with full spring pressure as well. That is virtually impossible to find with most rockers
Most rockers are too long to achieve minimal sweep and still be inside 1/3 of the valvetip. There's no way you can get rid of push rod arc but you can minimize it with proper geometry. Yes it is a blanket statement because geometry is geometry. Rules are the same no matter what it says on the box sticker.

That's not saying you can't get your own custom rockers. Miller builds a rocker with different spec. So can you.

engineguyBill
Expert
Expert
Posts: 736
Joined: Fri Feb 26, 2010 11:15 am
Location: Gold Canyon, AZ

Post by engineguyBill » Sat Aug 26, 2017 12:35 pm

Schurkey wrote:Perhaps I'm misinformed.

MILLER is big on MID-LIFT geometry.

CRANE was big on QUICK-LIFT geometry.
http://www.hotrod.com/articles/ctrp-060 ... cker-arms/

There used to be a Crane Cams animation of the rocker motion, but I can't find it anymore.

MID-LIFT and QUICK-LIFT are the same theory. Very possible that Crane coined the name QUICK-LIFT to avoid conflicts with Miller's patents. Back around 2004 to 2008, the QUICK-LIFT technology was illustrated in Crane Cam catalogs.
Bill

SAE Member (25+ years)
ASE Master Certified Engine Machinist
AERA Certified Professional Engine Machinist

"Do what you can, with what you have, where you are."
- Theodore Roosevelt

User avatar
MadBill
Guru
Guru
Posts: 12628
Joined: Tue Nov 15, 2005 10:41 am
Location: The Great White North

Re: Mid lift rockers

Post by MadBill » Sat Aug 26, 2017 5:26 pm

According to this:
http://www.enginelabs.com/news/quick-li ... f26bf74414
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.
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

Cogburn
Expert
Expert
Posts: 515
Joined: Sun Feb 12, 2006 12:21 pm
Location: South Dakota
Contact:

Re: Mid lift rockers

Post by Cogburn » Sat Aug 26, 2017 9:59 pm

Well, at least we had quite a few different choices of rockers depending on what a person wanted to do.

I guess the other side of the coin is that most people really didn't know what they wanted to do...

And to many it didn't make much difference.

stealth
Expert
Expert
Posts: 987
Joined: Fri Jun 30, 2006 9:37 am

Re: Mid lift rockers

Post by stealth » Wed Aug 30, 2017 9:23 am

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.
The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man.

Racerrick
Expert
Expert
Posts: 693
Joined: Sat Sep 24, 2005 10:52 am

Re: Mid lift rockers

Post by Racerrick » Wed Aug 30, 2017 10:09 am

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.
I agree and set all my rockers so the 2/3 of the sweep occurs in the first 1/2 -2/3 of the lift. IMHO Mid lift is the wrong way to go. I read an article a long time ago that the roller tip stop rolling once the pressure gets above a certain amount like 350

DaveMcLain
Guru
Guru
Posts: 2685
Joined: Thu Jan 06, 2011 8:57 am

Re: Mid lift rockers

Post by DaveMcLain » Wed Aug 30, 2017 10:24 am

Racerrick wrote:
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.
I agree and set all my rockers so the 2/3 of the sweep occurs in the first 1/2 -2/3 of the lift. IMHO Mid lift is the wrong way to go. I read an article a long time ago that the roller tip stop rolling once the pressure gets above a certain amount like 350
You have to remember though that Miller's concept of Mid Lift geometry isn't just about the valve stem end of the rocker arm it is all about optimizing both sides of the rocker, pushrod as well as valve stem ends.

Paul Kane
Member
Member
Posts: 76
Joined: Fri Feb 02, 2007 12:49 am
Location: SF Bay Area, CA
Contact:

Re: Mid lift rockers

Post by Paul Kane » Wed Aug 30, 2017 7:23 pm

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).
_____________________________________________
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.
_____________________________________________
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.
_____________________________________________
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.
_____________________________________________
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.
_____________________________________________
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.
_____________________________________________
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.
_____________________________________________
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!"
_____________________________________________
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.
_____________________________________________
We're On The Web; Click Below:
High Flow Dynamics
Performance Components for the 429/460 Engine Family


View our eBay auctions: click HERE.

Steve.k
Pro
Pro
Posts: 333
Joined: Sat May 28, 2016 10:41 am

Re: Mid lift rockers

Post by Steve.k » Wed Aug 30, 2017 9:29 pm

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.
_____________________________________________Thanks for info Paul. A good freind of mine who frequents the 385 forum bought the rockers from you at that time(Mark laczo) after i did some engine work for him. I thought they be a nice addition for this project.

Post Reply