I would think that the ratio would change somewhat depending on what part
of the rocker tip is contacting the valve. As the rocker depresses the
valve, the place where it contacts the valve moves outward from the rocker
shaft slightly the whole way down. So, the ratio would be less at smaller
openings than at larger openings.
- Tony Drews
At 02:50 PM 1/12/2005, Larry Young wrote:
>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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