Rocker Arms

[Alan Roehrich]

With a given tappet diameter, especially a flat tappet, there is an absolute limit as to how fast you can accelerate that tappet. So, given the tappet diameter, and a factory rocker ratio, there is a design limit on how fast you can accelerate the valve. Increasing the rocker ratio allows you to accelerate the valve faster. So, if you reduced your maximum lobe lift in order to use a higher ratio rocker, you'd be disguising a method of exceeding the design limit of the original valvetrain with regards to valve acceleration.

When you have a limited amount of lift, the secret to power, within reason, is how fast you can get to that lift limit from the valve being on the seat, how long you can hold it there, and how quickly you can get it closed. It's called, in general terms, "area under the curve". Again, this is a generalization, not an exact rule. For a given combination, there is an ideal, that combination may or may not be able to achieve that ideal. And that ideal may not always be the maximum amount of "area under the curve".

It is really hard to explain this, especially using generalizations as opposed to actual examples and the math involved. That's about as clear as I can make it here.