Rocker Arms

Dwight Southerland · 05-07-2010, 03:58 PM

The higher ratio rocker arm will increase any action ground into the camshaft profile by a mathematical amount. One of the limitations of how radical a camshaft profile can be ground is the lifter diameter. So, when the camshaft has been designed to maximum acceptible rate of lift change dictated by the lifter diameter, then there is no more that can be done to make the valve open any more at a given lobe lift. The higher rocker arm ratio allows a little bit more lift at a given lobe lift, hence "more area under the curve". Also, you can grind a faster ramp into a camshaft profile if the lobe lift is less, also providing for more area under the curve.

See what Alan said above. If I could draw pictures here, it would be easier to see.

05-07-2010, 03:58 PM	#32
Dwight Southerland VIP Member Join Date: Dec 2001 Location: Arkansas - In the middle of everything. Posts: 2,002 Likes: 64 Liked 783 Times in 195 Posts	Re: Rocker Arms The higher ratio rocker arm will increase any action ground into the camshaft profile by a mathematical amount. One of the limitations of how radical a camshaft profile can be ground is the lifter diameter. So, when the camshaft has been designed to maximum acceptible rate of lift change dictated by the lifter diameter, then there is no more that can be done to make the valve open any more at a given lobe lift. The higher rocker arm ratio allows a little bit more lift at a given lobe lift, hence "more area under the curve". Also, you can grind a faster ramp into a camshaft profile if the lobe lift is less, also providing for more area under the curve. See what Alan said above. If I could draw pictures here, it would be easier to see.