Rocker sharfts and shims - whats your thinking??????????

[Lee.C]

As a few of will have seen I am now making some changes to my customers 1915cc type1 motor
http://cal-look.no/lounge/index.php/topic,10301.0.html

we are moving up to a Engle120/cb performance stock style 1.25:1 rockers and 9mm rhino feet adjusters/3/8th Ali pushrods

BUT my main question is about the shims under the rocker sharfts - There is currently 5.5mm of spacers under both rocker sharfts 

Now I understand that once heads have been "flycut" for more CR you may need shims to get the correct rocker geometry but is it "good practice" to have soo many shims?
Whats your thinking guys 

Wouldn't it be better to reduce the number of shims and run a shorter pushrod 

Let me know your thoughts guys 

[TexasTom]

With over .200" of shims I would think there must be something quite wrong with your geometry and or pushrod length.
Remember, you must find the proper rocker geometry first, then measure for correct pushrod length.
Have you checked the pattern made by the rockers on the valve tips? That's what I do first ...

[Lee.C]

With over .200" of shims I would think there must be something quite wrong with your geometry and or pushrod length.
Remember, you must find the proper rocker geometry first, then measure for correct pushrod length.
Have you checked the pattern made by the rockers on the valve tips? That's what I do first ...

Thanks for dropping in dude - I have been thinking "something" is out/wrong 

The motor currently has 280mm pushrods - which I think is LONG, This is only a 1915 with a 69mm crank (not a huge stroker) I mean my little 1641 with less cam AND less rocker BUT the same 69mm stroke only needs 277mm pushrods  so surly with more cam and more rocker the pushrods MUST be need to be shorter 

But I am also in a little bit of a "Catch 22" as how set the rocker geometry WITHOUT knowing the pushrod length and how do I know the pushrod length without doin the valve geometry - do you get what I mean  should I just use my adjustable pushrod and get a "rough" length

 

[louisb]

Check this out.

http://www.cbperformance.com/Oct2005.asp

--louis

[Lee.C]

Check this out.

http://www.cbperformance.com/Oct2005.asp

--louis

VERY handy article - cheers dude  Explains ALOT