AHhhh! I get it!....

The 135 would have more sharp of angle then the 147. Which means the valve on the 147 would open quicker, because of a steeper lobe angle. Also because of the steeper angle the lobe is slightly wider, which is the increased duration...

The time (in degrees) it takes that valve to reach that lift (.200") would change. If the lobe is wider there it creates a steeper angle.

It makes sense in my head. I can see it. Kewl! ...


Two cams can have the same lift and duration but the shape of the lobe itself differs. The intake side might be steeper, but the top of the cam (peak) might have to be flatter to maintain that duration. As far as the same lift, the lobe might not be exactly 'centered', steep open and gradual closing.

 

exactly, like a concave camshaft lobe could have the same lift and duration as a convex lobe curve, but the concave one will have a higher ramprate and be closer to maximum lift for longer.