Why Roller Rockers....
Seasoned HDF Member
Joined: Nov 2006
Posts: 12,878
Likes: 5,449
From: la la land jerzey
it is a well used function in automotive mechanical engineering --- you don't get it I don't care -
the way your carrying on you need to turn the heat up on your safe space - your in a mans forum you feel offended / confused so what
the way your carrying on you need to turn the heat up on your safe space - your in a mans forum you feel offended / confused so what
Last edited by johnjzjz; Feb 22, 2019 at 04:53 AM.
Banned
Joined: May 2018
Posts: 4,576
Likes: 978
From: Viet Vet, crossroads
There you go again with your Fking insults for an answer you instigated.
Why?
Brillant, right?
You are a self-anointed SCREW ball, blathering a lot of BS.
All the power you must have had was between your legs in the motorcycles, and not between your ears?
This is a HARLEY forum and you inferred that (we) are so stupid as to not know how to adjust
rocker geometry just with Pushrod length.
Your reference to A yellow-paged book and all and a partial quote from it.
You are very misleading or just ignorant?
This IS NOT an automotive forum.
You seem to know this as you bragged about it with your pix of motorcycles.
Perhaps you can be princes and dance around some more with your checkered flag for answers?
If anyone needs a GD safe circle it is you, now go get a cry closet too for a full set of tools.
Now IDC about you or your race shop either.
All you did here was nothing.
You just felt a need to Brag.
BFD
Please!
no more strip teases for answers as I know you are a stuffed brain.
Grand HDF Member
Joined: Nov 2009
Posts: 4,315
Likes: 1,663
From: Tampa
Because I guarantee to you, if you only adjust pushrod length all that will happen is the hydraulic lifter will pump up until its max travel limit, then the valve end of the rocker will lift off the valve (or somewhere a gap will be present in the whole cam-to-valve stem mechanical system).
Club Member
Joined: Apr 2011
Posts: 5,804
Likes: 7,831
From: SE Louisiana
Here's a good video explaining rocker geometry.
On a stud mount rocker, the geometry is set with the trunnion height, the pushrod length is determined and a product of that.
It has to be corrected other ways on a shaft mount rocker design, and on a Harley v twin,
it goes a step further because you want the centerline of the pushrod ball to the centerline of the rocker shaft to also form a 90* angle at mid lift.
The goal is to get equal arc motion above and below the rocker shaft centerline for both pushrod and stem sides, not easy.
With lifts usually ran on a street motor, I'd say about .600 and down, it's less critical, and mostly done with the valve stem protrusion.
The rocker shaft, or trunnion height can be adjusted some by shimming or facing off the bottom of the rocker box, or the rocker support on a TC.
On a stud mount rocker, the geometry is set with the trunnion height, the pushrod length is determined and a product of that.
It has to be corrected other ways on a shaft mount rocker design, and on a Harley v twin,
it goes a step further because you want the centerline of the pushrod ball to the centerline of the rocker shaft to also form a 90* angle at mid lift.
The goal is to get equal arc motion above and below the rocker shaft centerline for both pushrod and stem sides, not easy.
With lifts usually ran on a street motor, I'd say about .600 and down, it's less critical, and mostly done with the valve stem protrusion.
The rocker shaft, or trunnion height can be adjusted some by shimming or facing off the bottom of the rocker box, or the rocker support on a TC.
Grand HDF Member
Joined: Nov 2009
Posts: 4,315
Likes: 1,663
From: Tampa
Finally, THANK you!
I suppose valve stem height could be incorporated onto a Harley application to get that centerline/90 degree relationship you mention above on higher lift applications, but as long as we've got a fixed pivot point for the rocker we'll never be able to achieve optimum rocker height without very invasive machine work and trickery.
Edit: I just watched that video, now I wanna see where my Harley is. If the motor was on a bench I'd be out there right now getting started. Considering it's a fixed height it would be a testament to how much Harley engineers gave a **** about rocker geometry when they designed the engine.
I suppose valve stem height could be incorporated onto a Harley application to get that centerline/90 degree relationship you mention above on higher lift applications, but as long as we've got a fixed pivot point for the rocker we'll never be able to achieve optimum rocker height without very invasive machine work and trickery.
Edit: I just watched that video, now I wanna see where my Harley is. If the motor was on a bench I'd be out there right now getting started. Considering it's a fixed height it would be a testament to how much Harley engineers gave a **** about rocker geometry when they designed the engine.
Last edited by Mattbastard; Feb 22, 2019 at 07:52 AM.
Cruiser
Joined: Oct 2016
Posts: 230
Likes: 156
From: Florence Oregon
Sorry, you got sucked into this. Some folks will never get it and as you say that's ok. This illustrates the reason I will never discuss my mods with a forum, there is usually just a lot of useless ideas and way too much ego.
Banned
Joined: May 2018
Posts: 4,576
Likes: 978
From: Viet Vet, crossroads
That video was enlightening!
(It is just TOO bad the HUBRIS from some is not.)
Albeit as Harley people I learned a lesson the hard way.
Cams are listed with the lift, but AFAIK this is the only world where the rocker ratio is included.
Not so anywhere else.
(It is just TOO bad the HUBRIS from some is not.)
Albeit as Harley people I learned a lesson the hard way.
Cams are listed with the lift, but AFAIK this is the only world where the rocker ratio is included.
Not so anywhere else.
Last edited by Kingglide549; Feb 22, 2019 at 09:14 AM.
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,080
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From: Ohio
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Banned
Joined: May 2018
Posts: 4,576
Likes: 978
From: Viet Vet, crossroads
Finally, THANK you!
I suppose valve stem height could be incorporated onto a Harley application to get that centerline/90 degree relationship you mention above on higher lift applications, but as long as we've got a fixed pivot point for the rocker we'll never be able to achieve optimum rocker height without very invasive machine work and trickery.
Edit: I just watched that video, now I wanna see where my Harley is. If the motor was on a bench I'd be out there right now getting started. Considering it's a fixed height it would be a testament to how much Harley engineers gave a **** about rocker geometry when they designed the engine.
I suppose valve stem height could be incorporated onto a Harley application to get that centerline/90 degree relationship you mention above on higher lift applications, but as long as we've got a fixed pivot point for the rocker we'll never be able to achieve optimum rocker height without very invasive machine work and trickery.
Edit: I just watched that video, now I wanna see where my Harley is. If the motor was on a bench I'd be out there right now getting started. Considering it's a fixed height it would be a testament to how much Harley engineers gave a **** about rocker geometry when they designed the engine.
For street its gooder enough, but for satisfaction or competition, it is not.
The only EZ way to cure it is to modify the tips of the rockers and that is what the racers do.
The big rocker shaft may not be ideal, but works for HD.
