rocker geometry issue

[norbs]

Seems that I can;t get the contact centred, no matter what pushrod length I try. I have been reading that it does not have to be centred. I do not want to shim the shafts, How do i determine the correct pushrod length? It seems it only moves how far the adjuster is in and out...

From Jim Miller..
Rocker geometry is NOT where the
roller (or contact point) is at on the
top of the valve. Forget that. Rocker
geometry, especially is NOT the idea
that you want to place the roller or wear
pattern (shoe tip rocker) in the “middle
of the valve.” Forget that, too.
The valve tip is everything.

 

[Chuck Leeper]

Are those keepers supposed to be used w/ lash caps????
Valves sunk into the head?

 

[norbs]

They can be used with lash caps, but its not a must. The valve height is shown , yes they are pretty deep.

 

[norbs]

I found this article on geometry, seems I can calculate the amount the shaft is out, but if I shim the shaft and use external oiling as planned then it will leak?

http://www.aera.org/ep/downloads/ep10/EP04-2010_20-30.pdf

 

[geno]

Seems that I can;t get the contact centred, no matter what pushrod length I try. I have been reading that it does not have to be centred. I do not want to shim the shafts, How do i determine the correct pushrod length? It seems it only moves how far the adjuster is in and out...
View attachment 170936

Are you talking about centering the rocker roller on the valve steam? The roller needs to start off on one side and roll across the valve stem and end up on the other side at full lift. If its starts off in the center it comes close to falling off the edge of the valve stem at full lift.Maybe this is not what your talking about? But like Chuck said maybe it needs a lash cap..

 

[norbs]

Are you talking about centering the rocker roller on the valve steam? The roller needs to start off on one side and roll across the valve stem and end up on the other side at full lift. If its starts off in the center it comes close to falling off the edge of the valve stem at full lift.Maybe this is not what your talking about? But like Chuck said maybe it needs a lash cap..

Yes I am, but I dont think its that important, according to the article I posted, the geometry has to be correct. I will have to measure it all and see what I come up with, lash cap may not be a fix.

 

[geno]

Yes I am, but I dont think its that important, according to the article I posted, the geometry has to be correct. I will have to measure it all and see what I come up with, lash cap may not be a fix.

Its very important that the roller does not come real close to rolling off the edge of the valve stem at full lift and start trying to fall off the edge of the tip. The (travel) should be as close to center as you can get it I hope im not coming across like a know it all because im not but i do know a few things...

 

[norbs]

Its not falling off the edge its just offset a bit Lets do the math and see what it says. Ive come up with the following formula based on the article. I also agree on what your saying.

ROCKER SHAFT DIA =R
ROCKER TIP DIAMTER=T
STAND HEIGHT= SH
STD= CONSTANT
X =CONSTANT

NET ROCKER LIFT= (CAM LIFT X ROCKER RATIO )- LASH

1/2R + 1/2T =STD

STD - 1/2 NET ROCKER CAM LIFT= X

SH - X = =+/- SHIM HEIGHT NEEDED FOR SHAFT SHIM

P.S I hope Donnie has done his math on his setup like this!

.4065+.2715=.678 STD

.678-.295=.383 X

.210-.383=-.173"



rocker shaft dia=.813/2= .4065
roller tip dia =.543=.2715
1/2 net lift =.295
SH=.210


Means the shaft has to be raised .173" OUCH! to keep the arc in the center of the valve.

 

[geno]

Im out of here before im told by the teacher that the planets need to be aligned first The botton line it thats what your trying to achive.While your at it check the pushrods for clearance in the heads if your going to run larger diameter push rods then were in it. I had to do some clearnce work on my heads to fit 7/16 push rods.Also make sure you check the heel of the rocker for clearance of the retainers. You can get away with a smaller pushrod on the intake than the exhaust.

 

[Alky V6]

I'd love to help here, but I don't want to appear to be a know it all, so I'll bow out. Good luck.

 

[geno]

I'd love to help here, but I don't want to appear to be a know it all, so I'll bow out. Good luck.

Go ahead Doni put in my 2 cents and i wont say a thing i swear.

 

[BlownV6]

Are you talking about centering the rocker roller on the valve steam? The roller needs to start off on one side and roll across the valve stem and end up on the other side at full lift. If its starts off in the center it comes close to falling off the edge of the valve stem at full lift.Maybe this is not what your talking about? But like Chuck said maybe it needs a lash cap..

I disagree with that set up. Roller tip should start inside of the CL of valve and pass over the center as it lifts and end up back to the original starting point inside of CL at full lift. At least thats how we do it here???? Mike

 

[norbs]

Donnie, I need your input on the math part of this, just put your other issues out of the way for now, and give me some technical feedback if this guy Jim Miller knows his math? I understand it kind of, but I think the concept is to minimize the sweep area , not so much where the contact area is?

 

[geno]

I disagree with that set up. Roller tip should start inside of the CL of valve and pass over the center as it lifts and end up back to the original starting point inside of CL at full lift. At least thats how we do it here???? Mike

I think we are saying the same thing?
To me the roller travel across the stem should be centered or as close as possible.

 

[BlownV6]

Ok , I looking forward to BG Mike

 

[geno]

Me also Mike
I can meet you in person and put a face to your name

 

[norbs]

After further research unless someone can make me at least a .150" rocker shaft shim this is not fixable. I will have to run it with improper geometry. It will just lose lift and wear the guides out faster.

 

[BlownV6]

You need something like this??? .140" thick. You dont want to know what these cost me. $80.00 shipped to your door if your intrested. Mike

 

[norbs]

YES Mike they would be great! How did you ever get them? What are they made from?

 

[BlownV6]

They are alum billet 6061. I had the same problem years ago and had them custom made. Yea been there and done all that!!! Paypal buickv6@hotmail.com and I can ship them on monday for you. Mike