Computer Lobe Profile Data

It's good to see some people learning more about camshafts and cam profiles. Having the equipment and software to measure and analyze cam profiles is a great tool to help you learn. Obviously you have to know how to use the equipment and be able to understand the data. You must also be aware of the limitations of your equipment.

Comparing cam profiles from different manufacturers will help you see different approaches to cam design. It's good to look at the overall basic design and not fixate on specific numbers. Most of the numbers are output numbers from the design input data. The results from the calculations. The designer does not generally try to create those exact numbers but rather have the output numbers fall into a specific range. There is usually a maximum value for the output numbers. The maximum velocity is determined by the flat tappet face diameter and the maximum acceleration is determined by the radius of curvature on a roller profile. Different tappets and different  profiles will have different maximum values. There are also special programs that allow lobe profiles to be designed that could not be designed with conventional programs. These programs use different techniques to control the maximum values. These techniques can be seen in the profile data and the graphs.

Today there are many different types of lobe design programs and I certainly have not used them all and do not know how they all work. I'm sure some programs will design a finished lobe from just a few input numbers. Other programs will involve the designer inputting different numbers and be more of a trial and error approach. These are the types of programs that I use.

Looking at the output numbers and saying "that number is too high" or "that number is too low" is not a good way to analyze a cam profile. Most of the computer lobe profile data I see is really not very good. The machines are not capable of producing the resolution necessary to truly analyze a lobe profile. The acceleration and jerk values are useless. Many users do not even look at the jerk values. The lift and velocity values are usually acceptable and the duration values are useful. There are different types of smoothing techniques that can help make the profile data usable and allow the lobes to be analyzed. Hopefully your program has one. You need to use the smoothing feature that came with your software. Using the smoothing feature will change the output data but the output data is mostly useless if you don't. That is the main problem with these machines. Congratulations if you have an Adcole machine or the Andrews Products EZ Cam. Both of those machines will produce excellent data.