A little more information on the input data.

DURATION - The duration at .050 and the lift are usually already known inputs when designing a cam profile. The duration input number will adjust the duration of the profile. Generally the focus is the duration at .050 but it can be anywhere. The angle on the lift table is 1/4 of the crankshaft duration.

NOSE ACCELERATION - The nose acceleration is the lowest acceleration at the nose of the lobe (0-degree). The velocity is decreasing to zero so the nose acceleration is a negative number. The number is usually between -.00015 and -.00035. Changing this number will change the entire profile. Nose acceleration is a main input.

RAMPS - The input numbers for the ramps were mentioned in lesson two. The valve closing velocity is usually under 40-inches per second for a modern high-end valve train. Other applications are around 30-inches per second. Tappet lash opening velocities are usually less than .002-inches per degree for a solid tappet. The same ramps can be used with different profile designs. New ramps do not have to be designed for each profile. Save your ramp designs.

DATA POINT - This is not necessary to design the lobe, it is just for information. It is the tappet lift at top dead center depending on the indexing of the camshaft in the engine. The angle on the lift table is 1/2 of the crankshaft angle.

OFFSET - Amount the lifter bore is machined with a rotational offset to the camshaft lobe. Can be a positive or negative number. Use 0.000 unless the offset is known.

EXPONENTS - Used in the mathematical equations in the program to design the cam profile. Changing any exponent will generally affect the entire profile. Each exponent must be different. The first exponent is usually the number two. Exponents are main inputs.

My lobe design form will give me the duration, lift, base circle diameter, hydraulic or solid profile, flat or roller tappet, rocker arm ratio, some engine details and the application. That gives me all the information to design the lobe profile. If you like to work with valve lift data, that's fine, just use your valve lift curve and rocker arm ratio and work backwards.

The duration input number will determine the duration at .050 (or anywhere). This number is also the angle on the lift table where the ramp and the profile meet. If the ramp has a height of .020, the duration input number will also be the duration at .020. The nose acceleration and the exponents will be the inputs used to "fine tune" the cam profile. The other inputs have already been determined and will not generally need to be changed. As you can see there is no "magic" involved in this. Just a bunch of numbers that will make up the lift and duration of the lobe profile. The velocity, acceleration, and jerk numbers are important to look at and understand how they affect the profile. Any magic is in the cam designer's knowledge and experience.

The last and most important step is to make the camshaft. If you are a camshaft grinder, use the lift table to make a model lobe and then a master plate or send the lift table to someone that can CNC a master plate for you. If you have a CNC cam grinder, you know what to do. If you are not a camshaft grinder, send the lift table to someone that can manufacture the camshaft for you. Below is my valve timing sheet to go with the finished camshaft ground on 108-degree lobe separation with 3-degrees advance.

This is an actual Reed profile designed with this software many years ago. It can be used as a starting point and then go in any direction you like. This is the best way to start learning, just plug in different numbers and look at the results. You will eventually see patterns and learn what inputs do what. It was one of the few cam design programs at the time but it works the same as any polynomial program today. If you didn't keep your MS-DOS computer and printer this software will also run using DosBox-X on a modern computer. I am using DosBox-X for these lessons. I put everything on a flash drive and that basically creates a DOS computer on the flash drive. The DosBox-X program is free to download (https://dosbox-x.com/). This lobe design program does honestly work best in an MS-DOS environment as it was originally created that way.

The last stage in the design process is to combine the four sections together and create the finished lobe profile. The four sections are the (1) opening ramp (2) opening profile (3) closing profile (4) closing ramp. Being able to design each one of these sections separately gives the user a lot more control over the lobe design. Not all programs are written this way. Since this is a symmetrical profile the four sections are not needed but when designing an asymmetrical profile they are very necessary.

When designing the ramps and profiles you will need to name and save them. The last stage in the process will use those names. Just follow the program instructions to combine the four sections and create the finished cam profile. The output data will be a graph of the profile and the lift table in 1-degree increments printed on one piece of paper handy for milling a model lobe. The lift table can also be manually programmed into a CNC machine or converted into an .s96 file. The last program (readdata.exe) in the software package will display and print the ramp and profile design data that has previously been saved. Ramps are saved with a .rmp extension and profiles have a .prf extension. Overall the lobe design process is not that difficult but certain profiles can be time consuming to design. Again, it is a trial and error process.

I don't know this to be a fact but I would guess there is some lobe design software that will pretty much design a finished lobe with just a few simple input numbers. It probably wouldn't be affordable but I'm sure one does exists. That type of software would eliminate a lot of knowledge for the person using it. A major problem in the manufacturing industry today. Whatever design software is used the end result is the same. I use the term "maxed out lobe" for a lobe design that has reached all the limitations for the application it was designed for. It doesn't matter how the lobe is created, it is what it is. The lobe could be designed with some super special software program, drawn out on a piece of paper, calculated with a slide-rule, designed with a spreadsheet program, or created out of someone's brain and written on a piece of paper. The finished lobes will all be the same. Once you have reached that maxed out lobe, that's as far as you can go. All the parameters have been reached. The area is the same. Just as the angle of a set of stairs or the pitch of a roof, the lift curve can only be so steep.

Below is the input and some output data for the profile design program. It includes the data from the ramp we just designed. The opening side of the profile will start at the end of the opening ramp and end at the nose of the lobe which is 0-degree. The closing side of the profile will start at 0-degree and end at the beginning of the closing ramp. In this case the opening and closing side of the lobe profile is the same along with the opening and closing ramp (symmetrical). Just like the input data for the ramp design this is also very difficult to teach. You are creating four sections of the cam profile. Another program will put all of the sections together. Scrolling through the lift table and looking at the graph will allow you to analyze the profile and decide if you want to make any changes.

Some of the profile input data may be confusing but most of this has been described in previous posts. Be sure to go back and read all of the posts and take notes. This stuff is very difficult to comprehend for someone with no previous experience. Running different numbers and looking at the results is a good way to learn.

DURATION = [angle where the ramp and the profile meet, controls the amount of duration]
CAM LIFT = [maximum lift of the profile]
NOSE ACCELERATION = [minimum acceleration at the nose of the lobe, negative number, affects the entire lobe]
RAMP HEIGHT = [data from the ramp design]
RAMP VELOCITY = [data from the ramp design]
RAMP ACCELERATION = [data from the ramp design]
RAMP JERK = [data from the ramp design]
DATA POINT = [tappet lift at top dead center, determined by the camshaft centerline]
BASE CIRCLE DIAMETER = [of the finished lobe]
LIFTER DIAMETER = [face diameter of the flat tappet, N/A for roller tappets]
OFFSET = [lifter bore rotational offset to the lobe, usually 0.000]
EXPONENTS = [for the polynomial equation, swells or shrinks the area of the profile]

To create the profile the input data is giving the the program the starting lift data which is at the end of the ramp, the ending lift which is the maximum lift at the nose of the lobe, the number of degrees between the start and end points which is the duration, and the ending acceleration at the nose of the lobe. The velocity and the jerk are both zero at the the nose of the lobe. The exponents will increase or decrease the rate of the profile and cause the area to increase or decrease. The program will take all of the input data and calculate the tappet lift at each degree of lobe rotation. From the lift table the velocity, acceleration, and jerk can be calculated. Pretty simple stuff, make sense?

We ended the last lesson with getting ready to design a ramp. Ramps are the entry and the exit areas of the lobe profile. There are very few absolute rules for designing a cam profile. The rules and limitations are usually set by the designer based on their experience. Hence the reason for all the discussion and opinions on the subject. That also applies to the ramps.

The opening ramp is pretty simple. It basically leads the tappet into the lobe profile. The opening ramp can almost be as fast as you want. Some profiles don't have an actual opening ramp designed into the profile. The profile ramps are usually noticeable on the velocity curve. They will show as a shallow sloped line on the opening and closing end of the velocity curve. After the opening ramp the tappet will increase in velocity and start accelerating. You can also see this on the velocity and the acceleration curves.

The closing ramp is more important because it determines the valve closing velocity against the seat. Too fast and it can bounce the valve off the seat and hurt performance and possibly damage parts. The closing velocity of the valve must be controlled. That is an absolute rule for designing a cam profile. The valve closing velocity is something that will need to be calculated.

If the opening ramp has the correct velocity it can also be used as a closing ramp. That will be the type of ramp design for our cam profile. Below are the input numbers for this ramp. Throughout the lessons, click on the picture to enlarge it.

I see everyone's hand go up to ask the same question, "Mr. Ingram, where do those numbers come from?" This is the part that is almost impossible to teach. Kind of like trying to teach someone how to paint a picture. Again, most of this stuff just comes from experience. I use the words "usually" and "generally" a lot because there is no absolute rule for most of this. The profile ramps have a height and a length just like a physical ramp or stairs have a rise and a run. The profile ramps will usually have a height of .020 or less and a length of 20-degrees or less. The velocity and acceleration numbers will obviously be small since the tappet is just starting to move or starting to close. The velocity will usually be .003 or less and the acceleration will be .0003 or less. All of the input numbers have to make sense (compute) to create the ramp and also the profile. All of my numbers are U.S. standard, no metric.

duration is in degrees - profile or crankshaft degrees, usually a known input
lift is in inches - profile or valve lift, usually a known input
velocity is in inches/degree - determined by the tappet face diameter for a flat tappet
acceleration is in inches/degree(squared) - usually .0004 or less for maximum
jerk is in inches/degree(cubed) - usually less than .00005 for maximum

We are now ready to look at the final ramp design. If your input numbers are good, then you are able to proceed. If not, you must try again. You will see a couple of screens including a graph of the ramp. Graphs are a nice way too see a big picture of what's going on. You will also see the lift table of the ramp design on another screen. The ramp and profile lift table can also be displayed in 1/4-degree increments. There are different types of ramps with different names. The engine does not care what type of ramp you use or what you call it. Again, the main thing about ramps is the valve closing velocity. The valve lash is usually part of the ramp but not always. As the lift increases for a given duration the velocity and acceleration numbers will also increase. Further distance to go in less time will always cause an increase in velocity and acceleration.

Cam designers tend to develop their own style and approach just as any skilled craftsman will do. I was very fortunate to learn this stuff while working at a major camshaft manufacturing company. I had access to highly sophisticated measuring devices and was able to analyze different camshafts from many manufacturing companies. That taught me a lot by being able to see how other camshaft companies were designing their lobes. I would recommend to everyone wanting to pursue this stuff to get a good "cam doctor" machine and measure as many different camshafts as you can. Along with a design program you will be able to duplicate or create your own designs after you acquire a basic understanding of lobe design.

Welcome everyone, sit anywhere you like. These first lessons will be a simple introductory approach to the cam profile design process using data and images from the design software. I would recommend taking notes, there will be too much information to try and remember. The two main programs of the software package are the ramp design program (ramplatb.exe) and the profile design program (prof386d.exe). Another main program (camplotd.exe) will create the finished lobe profile after you successfully design the opening and closing ramps and the opening and closing profiles. I say successfully because this entire process is trial and error until the desired lobe design is reached. If the numbers you enter do not compute, you can not continue.

I usually design the ramps first. The ramp is just that, a ramp. I like to use examples to help explain stuff. A motorcycle jump is an easy way to visualize a ramp. There is a launching ramp and a landing ramp. Each ramp is designed for a particular task. In cam design sometimes the opening and closing ramps will be the same. Sometimes the opening and closing profiles will be the same. This is known as a symmetrical profile, same opening and closing. We will design a symmetrical profile since it is simpler. It will be a hydraulic flat tappet profile for a small block Chevrolet 350 V8 engine.

Below is the ramp design input screen. The ramp will begin at zero tappet lift and end at some point that you choose. These input numbers are for the end of the ramp.

DISPLACEMENT = [tappet lift at the end of the ramp]
VELOCITY = [at the end of the ramp]
ACCELERATION = [at the end of the ramp]
LENGTH = [length of the ramp in degrees]
D.F. JERK = [degrees of final jerk at the end of the ramp, enter "A" and the program will automatically calculate the final jerk and the number of degrees]

Some designers don't pay a lot of attention to the ramp design. It's probably not as important today with better valve springs and a more ridged valve train. When I started designing, the ramp design was important, so I still pay close attention to it. The most important part is how fast the valve closes against the seat. Obviously engine rpm, rocker arm ratio, and valve lash will need to be taken into consideration when designing the ramps.

I keep a library of various ramp designs for different applications. Ramps that I have designed and used over the years and some that are taken from camshafts that I have analyzed. A lobe can actually be designed without ramps. Many of the original 3-arc cam profiles did not have ramps. Later with 6-arcs they did include ramps. Some modern profiles are designed without an opening ramp.

Just like the lobe profile, the ramps are created by the designer. Just like the lobe profile, it is a trial and error process. It all comes with time and experience. Don't get discouraged.

Wishing everyone a better year than what has come before. Thank you to all my customers that have trusted me to design your cam profiles. Nice to have met new folks interested in this stuff. Let me know what you think about the online cam profile design class.