Rocker Arm Ratio, what is it?

[911st]

Dose anyone know the ratio of the 911 rocker arms?

Also, if a cam has say .378" of lift, how far is the valve lifting off the seat?

[cgarr]

I was asking this a bit ago, here is what I got:

Rocker arm ratio?

[TimT]

Also, if a cam has say .378" of lift, how far is the valve lifting off the seat?

Why not just measure it to be sure?

[911st]

Craig,

Very interesting.

So about 1.45 for stock cams but it can vary with regrinds.

So my example of a .378" lift cam would be about .544" at the valve.

[911st]

Yes, measuring a real motor makes more sense.

I was more kind of wondering how the area between the valve and seat compared to the area of the ports.

It is kind of looking like the ports are mostly the limiting factor even with a low lift cam like on a 930.

Now I am wondering if higher lift cams are more about getting the valves open quicker than allowing more flow at full lift?