Camshafts and Compression
No you dope, Turk, nothing to do with DV.
I am sure Mike is a good guy, but he can still be wrong....
Below comes from Part 2 Tech of the B3 racing website. I do not know how to link it. Second sentence, 3rd paragraph. If anybody can link it, that would be good.
There are three errors.
"A roller tip was added to the nose of the rocker & everyting changed. No longer was the geometric point of rotation at the contact area of the roller tip & the valve tip. It is at the centre of the roller axle & maintains that point throughout the whole lift range, which means the ratio stays constant as well.......This is entirely different than the 'shoe' type rocker...
[1] The ratio varies as the rocker sweeps across the tip. On the valve side, the lever is from the fulcrum pivot to the contact point of the roller on the valve tip, not fulcrum to roller axle. Smokey Yunick explains, below.
[2] The ratio does NOT stay constant because of the changing position of the roller tip contact point, relative to the fulcrum.
[3] A shoe rocker works exactly the same as a roller rocker. The shoe can be likened to a large diameter roller. There is less ratio change because of the almost flat contact area. If you look at the chart in post #178, you will see there is very little change in the adv v measured lift of the stamped rocker.
You can see the ratio changes in the chart below.
No you dope, Turk, nothing to do with DV.
I am sure Mike is a good guy, but he can still be wrong....
Below comes from Part 2 Tech of the B3 racing website. I do not know how to link it. Second sentence, 3rd paragraph. If anybody can link it, that would be good.
There are three errors.
"A roller tip was added to the nose of the rocker & everyting changed. No longer was the geometric point of rotation at the contact area of the roller tip & the valve tip. It is at the centre of the roller axle & maintains that point throughout the whole lift range, which means the ratio stays constant as well.......This is entirely different than the 'shoe' type rocker...
[1] The ratio varies as the rocker sweeps across the tip. On the valve side, the lever is from the fulcrum pivot to the contact point of the roller on the valve tip, not fulcrum to roller axle. Smokey Yunick explains, below.
[2] The ratio does NOT stay constant because of the changing position of the roller tip contact point, relative to the fulcrum.
[3] A shoe rocker works exactly the same as a roller rocker. The shoe can be likened to a large diameter roller. There is less ratio change because of the almost flat contact area. If you look at the chart in post #178, you will see there is very little change in the adv v measured lift of the stamped rocker.
You can see the ratio changes in the chart below.