I don't think that is defection of the valve train due to spring pressure. I
got 1.45: as a rocker ratio when I checked it years ago with light tension
"checking " springs. The ratio will vary somewhat depending on how your
rocker arm geometry is set up. The farther away from the rocker shaft the
contact point between the rocker and the valve stem is, the higher the ratio
will be because the lever arm length is longer. Raising or lowering the
rocker shaft (or the end of the valve stem, or regrinding the end of the
rocker arm and changing the geometry of the arc on the end of the rocker
arm) will all change the rocker ratio.
Greg
Solow
----- Original Message -----
From: "Larry Young" <cartravel@pobox.com>
To: <fot@Autox.Team.Net>
Sent: Wednesday, January 12, 2005 12:50 PM
Subject: Re: TR4 rocker ratio
> This question was raised a couple weeks ago. I thought is was time for
> a technical discussion. A couple years ago I decide to measure the
> rocker ratio. Using a dial indicator and degree wheel, I measured the
> lift curve at the cam (no rocker assembly). Then I installed the rocker
> assembly and measured the lift curve at the valve. I took the ratio of
> the two curves and got the graph at
> http://home.swbell.net/cartrip/RockerRatio2.gif . I was surprised and
> confused by the fact that I did not get a horizonatal line. Later I
> realized I'm looking at compression of the valve train. After measuring
> the valve springs constant and installed spring pressure, I was able to
> estimate a valve train stiffness of about 60,000 lb/in. Sounds like a
> big number, but with 100 lbs of seat pressure (150 lbs at the cam), you
> get 2.5 thousandths deflection. I guess this sort of thing is common
> knowlege in mechanical engineering circles, but it was news to me. So,
> even though the rocker ratio is 1.49 you don't see that much more lift
> at the valve.
>
> EDWARD BARNARD wrote:
>
> >My documentation is showing two different numbers for the stock ratio.
One is 1.49/1 the other is 1.5/1. Hope that is some help. - Ed
> >
> >Stutzman <stutzman@adelphia.net> wrote:what is the TR3/4 stock rocker
ratio? I always thought it was 1.4 but I can't
> >find it in the manuals.
> >bruce stutzman
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