Camshaft consumers have been getting more sophisticated over the years. Engine builders and even some individuals are checking their camshafts with a computerized cam profiler before installing them. Those not using computers are checking their camshafts with a dial indicator and degree wheel. This has caused the camshaft grinder to profile each camshaft on his own cam profiler before sending it to his customer. The camshaft grinder uses the actual data retrieved to create the camshaft specification card. This prevents having to explain later why the camshaft specifications do not agree with the card.
Years ago when computer designed cam profiles were becoming common, a model lobe was created from the design data in a milling machine and a cam profile master plate was then created from the model in the camshaft grinding machine. This was before CNC machines were used to make the master plate from the design data. The master plate is used in manually operated camshaft grinding machines to make the camshaft. The most popular machines are the Van Norman and Berco camshaft grinders. There are many of these machines used today to make camshafts. The machine uses a follow wheel to trace the master plate shape onto the camshaft. There are many videos on the internet showing the operation of these machines. Check them out if you are not familiar with how a camshaft grinding machine works. Between the cam profile design, the making of the model lobe, the making of the master plate, and the making of the camshaft, many errors are accumulated. I am not sure but I may have just let out a big secret. I always say, there are three different cam profiles for each design. The original design (1), the actual lobe on the camshaft (2), and the profile that is created in a running engine (3). Obviously, you want all three to be the same, but in reality, they are not. Today’s technology is allowing them to become closer. Making master plates directly from the profile design data using CNC machines has removed many of the errors experienced years ago. A well maintained Berco camshaft grinder and CNC produced masters, along with a skilled operator, will produce a wonderful camshaft. Back to the years ago. There was usually a big difference between the original cam profile design and the finished camshaft lobe. A decrease of around 2-3 degrees in duration and 0.003 in lift were common discrepancies. This was from the major camshaft grinders of the time. If the camshaft grinder created the specification card from the original design, and most did, the actual camshaft specifications did not mach. Most people did not analyze their camshaft at the time and the small differences in specifications were usually accepted. It was just considered the normal tolerance. Today, the consumer expects to receive a camshaft with all the lobes matching the specifications exactly. Unless the camshafts are being ground on CNC machines, it is very hard to deliver that kind of quality. Profiling the camshaft and using that data for the specifications, is the only way to make them match and please the customer.
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My last three entries were linked to articles that I thought were interesting. Together, they sort of created a camshaft time line. We learned a little about the early American development of the performance camshaft and the people and companies involved. We now know in today’s world, there is not a magic formula that can pick the perfect camshaft for the application. It seems the people that market these formulas do not have any reputation for being engine builders or have much experience running engine dynamometers (just thinking out loud). We also got a glimpse into the future where the mechanical camshaft and valve train will be non-existent. All this spans about 130-year period.
Cam profiles were initially shaped by hand with grinders, files, and abrasive materials. Models were created on paper with compasses, protractors, scales, and straight edges. The modern cam profile is designed using computers and software to run sophisticated mathematical equations until the desired valve motion is created. We now look at the early cam profile designs as crude and ridiculous compared to modern designs. The future valve actuated systems will make our modern cam profile designs also look crude and ridiculous. The mechanical camshaft and valve train, as we know it, has reached its peak. We have squeezed out all of the performance that is going to be possible. Stronger, lighter, wear resistant, CNC machined components, larger base circle diameter lobes, larger follow wheel diameters, the best valve springs and systems without valve springs, multiple OHC systems, finger follower systems, variable cam timing systems, the best cam design software, and so on. It has all been done. If you think you are doing something new, you are probably only catching up with technology. Even though the technology is here, many are not using it. The OEM world seems to be the most advanced. Look at the automobiles that can be bought today. Simply amazing! Power, efficiency, suspension, brakes, aerodynamics, electronics, and air conditioned. Much of the racing world is far behind in the available technology. That has not always been the case. It is all about money, I understand. It will be a very long time before the mechanical camshaft becomes obsolete. Until then, please keep me in mind for today’s modern cam profile designs. |
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