Rocker arm ratio?

[cgarr]

Trying to figure out the valve lift with a set of super cup cams and think I may have to nip off the guide top to clear it. I am showing around 1.47 is that pretty close?

Thanks

[racing97]

I have always found 1.44 to be the mean average, it changes a bit with the radius as it swipes.

reagards

[cgarr]

We were both pretty close: Elgin Cams is showing 1.45:1 avg as the ratio for our rockers!

[2.70Racer]

The rocker arm ratio varies with the diameter of the cam.
At the base circle, the ratio is approximately 1.4:1 for a stock Porsche cam.
If the base circle is reduced from the stock factory dimension as when a cam is reground, the ratio at the base circle can be less than 1.4:1.
For our purposes here we are interested in the ratio at the peak or nose of the cam lobe.
This again can vary. Typically it will work out to be 1.5:1.
To verify all of the above a simple inspection of any Porsche 911 rocker will show a wear pattern that runs between 13mm and 15mm wide.
The rocker touches the base circle of the cam nearer the tip of the rocker.
At the nose (high point) of the cam, the rocker is touching closer to the pivot of the rocker. With all this we get a wide wear pattern on the rockers.