cams

The lift of valve is very small and depends on the profile of cam. I think, you are trying to design cam.
Smallest on an average is around 2mm and maximum that I have heard is around 8.7 mm. This might be helpful to you.
<a href="https://www.tildentechnologies.com/Cams/CamDesign.html" target="_blank" rel="nofollow noopener noreferrer">Cam Design</a>
<a href="https://www.rbracing-rsr.com/camshaft.html" target="_blank" rel="nofollow noopener noreferrer">Camshaft Technology and Calculations</a>

IssueThe lift of valve is very small and depends on the profile of cam. I think, you are trying to design cam.
Smallest on an average is around 2mm and maximum that I have heard is around 8.7 mm. This might be helpful to you.
<a href="https://www.tildentechnologies.com/Cams/CamDesign.html" target="_blank" rel="nofollow noopener noreferrer">Cam Design</a>
<a href="https://www.rbracing-rsr.com/camshaft.html" target="_blank" rel="nofollow noopener noreferrer">Camshaft Technology and Calculations</a>

Ok, thanks for your reply.

I have found that the cams used to operate valves of IC engines are circular arc cams. I am trying to design a circular arc cam with 45 degree rise and 45 degree fall i.e the valve opens at TDC and closes at BDC (the ideal case). Say, I choose the lift to be 4mm.
Now, how can I determine the other two parameters which are - the least radius of cam and nose radius. Please help me with this.