After one-hundred years of people designing camshaft lobe profiles someone got on the internet (of course) and stated that they design "valve motion" not tappet motion. OK, so what does that even mean? Does that mean you know what the valve lift should be at every degree of crankshaft rotation for that particular engine combination and application? Congratulations if you have the ability to do that.

Valve lift or valve motion is just another piece of data. It is the tappet lift multiplied by the rocker arm ratio. The tappet lift table becomes the valve lift table when this is done. The same thing can be done with variable rocker arm ratio valve trains. You just need to know the rocker arm ratio at each degree of lobe rotation (easier said than done).

To manufacture a lobe profile the lift data must be presented at the tappet. Even if you have the valve motion (valve lift) it must be converted to tappet motion (tappet lift) before the lobe can actually be made. Kind of makes sense to just design the tappet motion and then look at the valve motion later if needed.

I supply an .s96 and a Landis .p file with each of my lobe designs. These are the programming files for CNC camshaft grinding machines. Both files are different formats of the tappet lift at each degree of lobe rotation. Tappet lift not valve lift.

Most camshafts are sold with a duration at .050 number. That is the crankshaft duration at .050 tappet lift for that lobe. Tappet lift not valve lift. That duration at .050 number comes from the tappet lift table. Unfortunately camshaft manufacturers do not supply the lift table to their customers. You can create your own tappet lift table with a degree wheel, the correct tappet, and a dial indicator. You can also send your camshaft to someone with a "cam doctor" and have them create you one.

I have some previous post about lift tables, be sure to read them first. July 2013, September 2022, May 2024.

The lobe consists of the opening side and the closing side. Zero degrees (0) is the nose of the lobe. It will be the maximum lift point. The opening side of the lobe will be from 0 to the beginning of the opening ramp. The closing side of the lobe will be from 0 to the beginning of the closing ramp. Each degree will increase from 0 as you go toward the ramp. The degrees are also called "events" in the lobe design world.

The .050 tappet lift will coincide with some event (degree) on the opening side and the closing side of the lobe. An asymmetrical profile will mostly have different events. Interpolation will probably need to be used to find the exact event number. This is a good way to see if your profile is asymmetrical and by how much and where. These events will also be needed to calculate the correct valve timing for an asymmetrical profile. The opening and closing events are added together and multiplied by two to get crankshaft degrees (the duration). Remember, the events are in camshaft degrees. The crankshaft turns twice the speed of the camshaft.

To work with valve events, just multiply the tappet lift by the rocker arm ratio. The .050 lift at the valve will now coincide with a different event (degree) but the duration is still calculated the same way. With a 1.5 rocker arm ratio, .050 lift at the valve will be 0.03333333 tappet lift (valve lift divided by rocker arm ratio). The 0.03333333 tappet lift will coincide with an event (degree) on the opening and closing side of the lobe and allow you to calculate the .050 duration at the valve. You can also create the velocity, acceleration, and jerk tables and graphs for the valve lift. Now you can compare lobes using valve motion (valve lift). The duration can be found the same way for any tappet lift or valve lift, not just at .050.

Most people are never going to see a lobe profile lift table, but if you have a camshaft that you really like, it might be a good idea to have one generated. Like I have said many times, "The lift table is the cam profile and it can tell you everything about the lobe".

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.

People are sometimes illogical when it comes to learning something new. It's almost like they have a fear of learning and avoid it. Reading is a great way of learning. The internet and especially YouTube is also a great way to learn something new. Today it's easy to learn something with very little effort. Many people don't use these resources and end up asking questions to someone that knows less than they do. They never even learn the very basics. Maybe this video can help those people.
https://youtu.be/qvJGr-BjybA?si=hpthVn9PqIXso__p

WOW! The end of another year. I have fortunately been able to watch many years go by and been able to learn something new each year. I have also seen many things change through the years, especially with technology. Some things have changed for the better and some things are definitely much worse than before.

The world of camshafts has honestly not changed very much through the years. Instead, people are finally starting to understand and use the technology that has existed since the beginning. Hopefully this website has contributed a small part to that understanding. Valve train components are getting better which allows camshaft lobe designs to move the valves faster and farther to make more power with more reliability. The valve train will generally need to change first before the lobe profile can change.

Many people are now using computers to measure and analyze their camshafts before installing them. Some are learning more about camshafts and lobe designs instead of relying on the manufacturers and their marketing gimmicks. Actual knowledge is always a definite advantage with anything. So keep learning.

Thanks again to everyone that has trusted me with their lobe designs. It was also nice to communicate with all the new people this year along with my regulars. Hopefully I was able to help. Everyone have a happy and prosperous new year.

Video about flat tappets and roller tappets and oil. It took 56-years for NASCAR to figure this out. Many other racing organizations need to also figure this out.

This subject is also mentioned on the website but I still get questions for information that I do not release. I do not release information on who I do cam designs for. I do not release information on the cam designs of my customers. I do not release information on how I design cam profiles or what software that I use. All of this "top secret" stuff is for the benefit of my customers and I think most of them appreciate that I do keep it confidential.

As I have said before, how a cam profile is designed or what software is used does not really matter. The person designing the cam profile determines the final lobe profile design. The knowledge and experience that the designer has will have more to do with the profile than the process used. No different than a plumber or an electrician. You hire the one based on their knowledge and experience. As far as not releasing information on my customers and their lobe profiles, well that should be obvious.

Hopefully everyone understands and I don't upset anyone for not answering your question relating to this subject.

Once in a while I will get involved in designing a cam profile that does not follow the usual parameters of lobe design. I call these "crazy cam profiles". Some of you may remember Rod Serling saying "you have just crossed over into the twilight zone" from the TV series. That is my feeling about these cam profiles.

These cam profiles are usually (but not always) used in applications with valve lift rules combined with low RPM engines and low valve spring pressures. These types of engines are very forgiving of the lobe profile design and allow you to get away with stuff that you normally could not.

One of the craziest lobe profiles I have seen involves designing a lobe with a lot of lift and then grinding away the excess lift to comply with the lift rule. This creates a lobe with much more duration than could be designed normally. The finished lobe looks awful on paper but works fine in the real world. The usual ways to create crazy cam profiles are by modifying the lift table, modifying the actual lobe, or just designing a radical profile. These crazy cam profiles are more common than you would think. These profiles have velocity, acceleration, and jerk curves totally different from a normal cam profile. The maximum values are usually much higher and the shape of the curves are fairly erratic. It is difficult to do but all the normal basic lobe design rules must be ignored.

These profiles are a good example of the "design world" and the "real world". As a lobe designer, it's good to get involved with these profiles. They teach you a lot about what you can get away with in the real world. Some of the stuff is very surprising.

If you are someone like me that has been around for a while, you probably remember the 1960's and 70's and the muscle cars of the time. I was 20-years old in 1975. I liked cars but I was more into Harley-Davidson motorcycles. It took less money to work on and build Harleys. I was building a 1949 Panhead chopper at the time. This is also the same year that I started grinding camshafts for Reed Cams, Inc.

Chevrolet, Ford, and Chrysler were all producing small block OHV V8 engines with more power than ever before. Big block engines were also being installed in cars. Each car Company had their own line of performance parts that were available to the public. Each Company had a following of fans that knew the best part numbers for each component. Engine blocks, heads, crankshafts, rods, and certainly camshafts. One of the popular Chevy 350 performance camshafts of the day was the GM 3849346. Also known as the "30-30" camshaft.

I have created my own design based on this camshaft with a modern approach. With this lobe design the camshaft can be manufactured for a flat tappet or a roller tappet. The tappet can also be a hydraulic or a solid. The lash is .009-inch for a solid tappet. The ramp designs are much better than the original .030-inch lash ramps and deliver the same running duration numbers as the original profile. The original camshaft was ground on 114-degree lobe separation with maximum lift at 112 ATDC on the intake and 116 BTDC on the exhaust. You can choose whatever lobe separation and indexing you would like based on your application.

Below is the tappet lift table in an .s96 format that will allow you to have the camshaft manufactured. Download the file and send it to your camshaft grinder. Give them the lobe separation and whether you want a flat tappet or a roller tappet camshaft. The Chevy 350 base circle diameter of the lobe is 1.220. The base circle diameter can also be larger for LS engines or other large camshaft journal engines. The roller wheel needs to be 0.750. Get the correct tappets and you are ready to go. A data file of the profile is also listed. Let me know how the camshaft works for you.

Here is what I look at when designing a cam profile or analyzing another cam profile. There are other things I look at but these would be the most common.

lobe lift
duration at 0.006
duration at 0.020
duration at 0.050
duration at 0.100
duration at 0.200
duration at 0.300
duration at 0.400
duration at 0.500
velocity curve
acceleration curve
jerk curve
radius of curvature
pressure angle
ramp designs
valve lash settings / valve contact

This data will usually give me an overall idea of the cam profile and a good comparison with other cam profiles in the same category. The lift table data is fine if the graphs are not available. Making graphs from the data is always an option. The radius of curvature and pressure angles will need to be calculated if that data is not available. Both are important so that information is necessary. There is much more to a cam profile than just the lift and the duration at .050. Unfortunately, that is usually all the information available from the camshaft manufacturer. Some sort of computerized measuring device will be necessary to easily obtain the other data.

I have added an archives to the "CAM TALK" page. It's basically an index to help navigate through all of the entries. It also allows me a way to reference an entry that may relate to something. Hopefully it will be helpful instead of just taking up space. Let me know.

Very nice cam profile graphs can be created from the lift table data if you know how to use Microsoft Excel. It's a little more involved than copy and paste but it's not too difficult. The same information is in the lift table data showing exact numbers but graphs are a good way to analyze a cam profile if you know how to read them. A lot of information can be quickly seen in the graphs. All of the graphs are important to look at but if you only had one graph, the acceleration curve is probably the one to have. In this sample a solid tappet cam profile is symmetrical and the accelerated ramps are designed with the lash settings in the "dip" area. This creates a gentle opening and closing of the valves. This ramp design is usually not necessary on the opening side but if the valve closing speed is not controlled the valve may bounce off the seat or possibly damage parts. The "bowl shape" on the negative side of the curve creates a gentle transition over the nose of the lobe allowing the tappet to easily follow the shape of the lobe. The conservative maximum acceleration will be easy on the valve train and springs. Overall this will be a cam profile that should not cause any unnecessary stress on the valve train. A lot of good information from just a quick look at the acceleration curve.

The lift, velocity, and jerk graphs are the other common curves. The lift and velocity curves should both be a nice smooth curve from zero to the maximum value. Any deviation from the nice smooth curve would indicate a problem with the design itself. The velocity curve will also reflect the type of ramp designs used. The jerk curve will show the changes in the acceleration. Big changes in the jerk curve are normal around the ramp to profile transition. The rest of the curve should be nice and smooth. Any deviation in this area would indicate a design problem.

The lift curve needs to have a resolution of four (.0001) decimal places. Three places at a minimum. The velocity curve needs five decimal places (.00001). The acceleration and jerk curves need eight decimal places (.00000001). That is one hundred-millionth! Your equipment will need to produce the lift table data in the necessary resolutions to create these graphs. Lower resolutions will produce jagged graphs that are useless. Unfortunately what most people use today does not produce quality graphs.

The lift table is the cam profile. I say that a lot. Kind of like the rise and run on stairs, the lift table shows the tappet lift at each degree of lobe rotation. If a dial indicator was placed on the tappet and the camshaft lobe rotated one degree at a time, the dial indicator readings would be the the lift table. Some lift tables may show increments of less than 1-degree. I have previous posts about lift tables so be sure to go back and also read them.

"The lift table shows the tappet lift at each degree of lobe rotation." It is very important to understand that statement. "Tappet lift", is any tappet, not specific. This is the rise (lift) of the tappet. It doesn't apply to any type of tappet, only the lift of the tappet. The same lift table can be for a flat tappet profile or a roller profile. It can be for a roller profile with any wheel diameter. The "tappet lift" is just that, the lift of the tappet. Remember that.

The actual tappet used will determine the final shape of the lobe. That is because of the contact point between the tappet and the lobe. The contact point does not stay on the centerline of the tappet. The contact point moves away from the centerline on a flat tappet and a roller tappet. The shape of the lobe and the contact point will determine the tappet lift at each degree of lobe rotation. Obviously if you put a flat tappet on a roller profile or vice versa you will get a different set of specifications. That is because the contact point is different on the flat tappet and the roller, make sense.

When someone orders a cam profile design from me they will get a .p file, an .s96 file, and a data sheet with the lift table. All of these are the profile lift table just in different formats for different applications. The .p file is used for the Landis CNC cam grinding machine, the .s96 file is used for most other CNC cam grinding machines. The lift table is part of the data sheet for the cam profile. Other important information is also on the data sheet. Most CNC cam grinding machines that I know of use the lift table to produce the cam profile. Apparently the CNC machines have built-in software to calculate the contact point for the actual tappet being used to produce the cam profile.

Sometimes customers will want to convert the lift table to cartesian coordinates (x and y). Using a direct conversion equation from the polar coordinates of the lift table to cartesian coordinates will not work. The contact point for the actual tappet being used must be considered in the calculations. The base circle diameter of the lobe also plays a part. Using a direct conversion will produce a shape that looks more like an inverted roller profile and is of no use. Physically drawing the profile using the lift table and the correct tappet will create the correct lobe shape. I am not a CAD/CAM person but that would probably be the best way to draw it.

Back in the day before CNC machines I would create a model lobe by using the lift table and a rotary chuck on a manual milling machine. This was a visually effective way of seeing and understanding the contact point between the lobe and the tappet. In this case the cutter is the tappet and it creates the lobe shape. I would use a flat face end mill for a flat tappet profile and a ball end mill of the correct diameter for a roller profile. Many original roller profile lift tables were used to produce a mushroom flat tappet profile. I just used a flat face end mill cutter instead of a ball end mill. Pretty cool. Today with CNC milling machines the model lobe can be produced using cartesian coordinates. This website may be of help for converting the lift table to the proper x and y coordinates. https://saltire.com/

Here is the profile graph and the model milling lift table for a popular NASCAR Winston Cup lobe profile we designed in the 1980's. This would be "top secret" stuff at the time. This is considered an old design compared to the lobe designs of today. It is an asymmetrical flat tappet lobe with a rate designed for high RPM and endurance. It has easy ramps with a running lash of .012 for rocker ratios of 1.5 or 1.6. It was designed with our software program for the 0.874 diameter flat tappets and valve springs used at the time. A lobe profile design today would probably dwell the maximum velocity on the opening and closing sides of the lobe. Different ramp designs would probably also be used. Today's lobe design would have more area with the same duration numbers at .020 and .050 and the same lift. The duration numbers at .100, .200, and .300 would be larger. The larger area is the major difference between a new lobe design and an old lobe design. Lighter and stronger valve train components make it possible to design lobe profiles with faster rates and more area. Camshafts with larger journal diameters are also an advantage. It would be interesting to analyze the NASCAR camshaft lobes of the 1960's and 70's. You need to know where you've been to know where to go.

Profile available for the MS-DOS Reed program.

This is the conclusion and summary of the previous five lessons. We have created the opening ramp of the profile, the opening side of the profile, the closing side of the profile, and the closing ramp of the profile. We then put all four sections together and created the cam profile. In all reality a fairly easy process if you have a computer program that does the math for you. You have to admire the people that did this stuff before the assistance of a computer or even an electronic calculator.

Here is my unique example of what the tappet will experience during its travel up and down the lobe. You need to image that you are the tappet. You are going up one side of a hill and down the other side. You start off walking up the hill (opening ramp) at around a constant pace (velocity and acceleration). Like walking up the stairs. At some point your pace will start to increase. You are now running. You will reach maximum acceleration first and then maximum velocity. If you are a flat tappet the maximum velocity will be determined by your diameter. A roller tappet will limit your maximum acceleration. If you exceed either limit you will fall down, skin yourself up, and roll down the hill. Basically the tappet and the camshaft will be destroyed. If you are not destroyed, your pace will start to slow as you reach the top of the hill (maximum lift).

From this point you will travel down the other side of the hill. You will go through the same velocity and acceleration forces just in the opposite direction. You will reach maximum velocity first and then maximum acceleration. Eventually you will slow down and stop at the bottom of the hill (closing ramp). You can follow along by using the profile graph showing the velocity and acceleration curves.

Velocity, acceleration, and jerk can be confusing. An easy way to understand these forces is in your car. The velocity is the speed, the reading on the speedometer. Velocity is usually associated with acceleration. Acceleration is how quickly you get to that speed. Jerk is the forward and backward movement that you feel when speeding up and slowing down quickly. That "jerky" motion. It can be very annoying. It is also very annoying in lobe profile designs. A lot of jerk creates a lot of stress in the valve train just like in the car. All of these forces are easy to experience while driving your car (try it). You want all of these forces to be nice and smooth, not to harsh and not to soft, just right.

As I have said before, the software only does the math. It is up to the lobe designer to create a good profile design. As you better understand these forces and how they affect the lobe profile, the better your designs will be. Some other calculations you will need to do are the maximum velocity for the flat tappet diameter, radius of curvature of the lobe, valve closing velocity, base circle diameter of the lobe, pressure angle between the tappet and the lobe, duration at different tappet heights, valve lift, and valve lash.

All of this stuff is just math, physics, and numbers. No magic. As long as your lobe design doesn't tear-up something, consider it a good design. It may not make as much power as you would like but that's ok for now. It all just takes time. Hopefully you enjoyed these introductory lessons to the cam profile design process. Depending on the response to these lessons, I can go further into the design process using more examples with more detail. Let me know if you have any questions or suggestions or if you want to purchase the program. Good luck to everyone. Class dismissed.

If you read my website regularly, you will notice changes in wording along with other changes. I am always re-reading and looking at the website and making changes, hopefully to make things easier to follow and understand. Nothing drastic, usually just changes in the wording. It may help you to go back and read things over again. I have edited the cam design lessons many times already since they were first posted. I'm sure I will change them some more.

I read a lot for the purpose of learning something new. I may read the same thing over and over until I understand it. That is the purpose of "CAM TALK". You must read and comprehend the material in order to learn something. It's like watching the same movie or video many times and seeing something new each time. I think there is finally enough information on the website now for someone to understand cam profiles and actually design a lobe profile using the proper software. There are definitions, descriptions, and examples for all the terms used in cam profile design. There are actual numbers and range of numbers to use for various parameters. This is all information I have not seen anywhere else on the internet or in books. I share this information because it is not easily found. I remember being very frustrated trying to find this kind of information. It is still frustrating. Many people involved in this stuff seem to be hard to talk with and very hush, hush about sharing knowledge. They will only sell you their knowledge. You must buy their books or pay to go to their seminars.

Carefully read all of my posts, take notes. If there is something that you don't understand, ask me. I am not one of those people mentioned earlier. I am glad to share knowledge and help. I know there are not many people that are interested in this stuff but I am a good source of information for those that are. If you are someone who already knows all about this stuff, please contact me and introduce yourself.

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.

I have been asked a few times about teaching automotive cam profile design. I enjoy sharing knowledge with like minded people but I don't have a logical way of actually teaching someone in person. I was thinking maybe I can do this online through the website. I don't have any desire to create a YouTube channel but I admit that would probably be the best approach.

I have an old 1980's DOS lobe design program that is for sale on the website. A very good program at the time, just a little hard to use today. I hate to see it go to waste so this may be a way to make use of it again. I would also like to keep the Reed cam profiles alive in the process. I know many customers thought that the Reed cam profiles were some of the best. Maybe some of those folks would be interested in this.

I am thinking about using the program to help teach cam profile design. I would go through the design process with Reed profiles and post it here on the website. It would be free to everyone but to really receive the full benefit the reader would also need to have the program. Once they becomes proficient with the program they may decide to pursue this further and purchase a more modern program and even start their own camshaft manufacturing company.

Apparently in the world of flat tappet camshafts the quality of the camshafts and/or the lifters has turned to absolute crap. I am not surprised and can see this happening since flat tappet camshafts are no longer used in production automotive pushrod engines. Basically it's the same thing that happened with the automotive engine oil many years ago. The chemical make-up of the oil was changed because the production car engines went to using roller camshafts and a different oil recipe was created than what was used with flat tappet camshafts and that oil became obsolete. Since flat tappet camshafts are no longer used there is not the quality control for these components that was there before. I would guess the major camshaft core suppliers will eventually quit manufacturing them. The racing industry only makes up a small part of the entire automotive industry. If you haven't figured it out yet, it's all about money.

I would guess the material make-up and/or the metallurgy has changed in the flat tappet components. Finding short-cuts in order to manufacture the components cheaper would obviously be the reasoning behind it. Manufacturing flat tappet camshaft cores and lifters is a very small segment of the automotive industry since the major car companies don't use them anymore. It's not worth the investment. Simple economics.

Simple economics also needs to be used to fix the problem. Racers and engine builders must unite together and protest against the flat tappet camshaft rules and refuse to use them. It will not take long before the race tracks will change the rules and allow roller camshafts to be used. Simple economics.

Sometimes fast rate, slow rate, or aggressive might be the term used. Like most camshaft terms, they are used in marketing to sell camshafts. What makes a cam profile fast rate or slow rate? What makes a cam profile aggressive? Sometimes the term only applies to the profile ramps, such as the ramps are fast or the ramps are slow, the ramps are aggressive.

If you look at enough cam profiles, some definitely move the valve faster than others. Basically the movement of the valve (or tappet) per degree of lobe rotation is considered the cam profile rate. Velocity is the actual term used when designing cam profiles. How quickly that velocity is reached is the acceleration which is also part of the rate. In flat tappet profiles the maximum velocity is determined by the tappet face diameter. Roller profiles will usually have a faster maximum velocity and most are about the same for a specific profile. The acceleration will need to be controlled on a roller profile to prevent excessive negative radius in the flanks.

Some ramps will open the valve faster, some ramps will close the valve slower. It's just all part of the design. If someone is trying to sell you a camshaft that has fast ramps than slow ramps are bad. If the maximum velocity is higher than it is better. Sound familiar. If you give-in to this type of marketing, read my last post. Maybe read it a few times, it is very short and to the point.

The best way to compare cam profile rates is by looking at the duration at the higher lifts. There is a reason most camshaft manufacturers do not publish duration figures past 0.050 tappet lift. Measure the duration at 0.100 intervals. Compare the duration numbers. If the camshafts are the same at 0.050 but one is larger at 0.100, 0.200, 0.300, and so on, the larger one has a faster rate. More importantly, it has a faster rate where is really matters. The faster rate at the higher lifts gives you more area under the lift curve. What goes on above 0.050 on a cam profile is a whole lot more important than what goes on below 0.050 as far as making power. Below 0.050 has more to do with the affect the cam profile has on the valve train (valve springs, push rods, valve seats, valve lash, etc.)

In a four stroke internal combustion engine turning 6000 rpm the valves are opening and closing 50 times a second. At 10,000 rpm that number increases to 83 times a second. Don't overthink this stuff or pay much attention to the latest marketing gimmicks.