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I've developed an unhealthy curiosity towards the Norris SS cam, the 620x11. Seeking any persuasive opinion and/or dissuasive discussion for enjoyable enlightenment. So, I'm putting it out there - as seems it's not a cam that V11 owners ever seem to install. True, I understand recommendations abound that the 620x10 is the go to usual suspect… However, an SP1000 owner is happily using it & I'm baffled as to why the Norris SS isn't one V11 owners haven't utilised…? SP1000 owner quote: "There are several good performance cams on the market. I fitted a Megacycle 620x11 to my wolf-in-sheeps-clothing SP1000 and in my opinion every streetbike should have one - not to mention racebikes. Why do I say this? My bike is a streetbike/commuter and I feel no loss of bottom-end performance and gains everywhere else. (I'm running LM2 heads - same valve sizes as the LM3 - and PHF36 carbs)." Btw, in the course of my travels I found this former published interview with Norris Barsumian which I include for those that might find it interesting as well. Interview: Norris Barsumian We Venture Into The World Of Camshaft Esoterica, Where A Little Means A Lot, If Going Faster Is The Goal. JODY NICHOLAS WITHIN THE SHORT SPAN of three years, Norris Performance Products has grown from a two-man operation to one of the most respected names in racing cams for both automotive and motorcycle engines. It's still not a large company, but it is growing steadily, and is constantly improving its products. Norris Barsumian is a motorcyclist who was previously involved with electronics, while Norris Baronian formerly held the position of general manager of Iskenderian Cams. Working together, they have produced cams for recordholding cars and motorcycles all over the U.S. Danny Macias, head of the Triumph-BSA racing effort in the U.S., has been using Norris cams fora couple of years, as has Harold Allison, the tuner of the Norton 750 which carried me to many victories at Ascot Park this past season. What, then, is the secret behind these fast machines? We feel that the cams played a very important part. One which we wanted to know more about. CAM LOBE DESIGN CW: Now Ilui! we know sonic oj the basic terminology regarding earns, could you explain a little more? Norris: Sure. On any cam there is an opening ramp and a closing ramp. They may be the same (symmetrical) or they may have different (asymmetrical) characteristics. Our cams for Triumph and Norton are symmetrical, but the Honda cams are asymmetrical, for a reason I’ll explain in a moment. Most of the actual lift occurs in the flank portion of any cam, but it’s important to have a good combination between the rates of lift of all three basic parts of the lobe. Eor example, a cam could be designed to have a rather quick-lifting ramp, and have the rate of lift slow down somewhat in the flank section. We’ve found that a maximum rate of lift of 0.007 in. per degree of crankshaft rotation works extremely well in the 650 Triumph. CW: What determines the amount of valve clearance, or "lash, "in any particular engine? HV know, for instance, that you set the valves for zero lift on a Royal ffnfield Single, but the figure for other machines is often in the region of 0.010 in. Norris: Valve lash is determined by the engine designer (or by the cam designer), and is directly related to the amount of “growth” experienced by the cylinder and valve train components when an engine gets up to operating temperatures. A Harley Sportster will run along with about 0.0 lb-in. valve lash when hot, but the clearance is nil when the engine is cold. Media Credit Media Caption Media Description Media Image Media Credit Media Caption Media Description Media Image One thing most people don't realize is that you can alter the characteristics of a cam merely by varying the amount of lash in the valves. You can squeeze down on the lash it you need a little more top end. or you can open up the clearance a little il the cam (like ours) has a long ramp area and gain a little mid-range power and torque. It s best not to overdo this, however, as too much lash will cause damage to certain of the valve train components, and too little could cause the valves to burn. Most people don’t realize that cams are “adjustable” like this, but it's best to get the information from the cam designer, or some authority, betöre making any radical changes. Another reason for valve lash is to allow the valve to sit on its seat and cool. There’s less you can do in this area with an overhead cam machine because of the lesser amount of variance between hot and cold clearances. Getting back to the asymmetrical lobe design of a Honda, it is because they use a finger-type follower that the lift ratio isn't the same on both sides. The cam rotates in only one direction, but the followers are on both sides of the cam. On one of the followers, the cam is picking it up from the back side of the lifter shoe, and on the other, it begins lifting on the front side. As the cam sweeps across the lifter either towards the central pivot point, or away from it. the ratio of lift is constantly varying. Hence, the cam lobe must be ground accordingly to obtain a symmetrical opening/closing rate for the valve. PROCESSING A CAM CW: What happens to a customer's earn w hen it comes in for a regrind? Norris: First, the cam bearings are checked to make sure they're not out of round, and I look to make sure there’s enough material on the lobes to permit a regrind. We then grind the cam and send it out for a special heat treating which doesn't distort it. After another check we send the cam back out for a double lubing. It’s first Parkerized (an acid and manganese iron high-temperature process which deposits a non-metallie lubricant into the pores of the metal) and then dry-lubed, using an aircraft process which involves baking. CW:7.v/;7 that like Microseal? Norris: It performs the same job as Microseal, but it’s not the same process. The main idea is to allow the cam lobe and lifter to “mate”; that is, to form a rubbing surface on each. Most cam lobe and lifter failures occur in the first few minutes of operation, before the rubbing surface is properly formed. We also include an assembly lube with our cams for the guys to use so that the parts stay lubed until oil pressure reaches them. It makes a big difference in the life of the parts. CW: What do you do when a cam has to he huilt up to get enough lift after regrinding? Norris: We use one of two processes, either heliare or acetylene welding. We use the heliare on most cams because the metal flows onto the lobe more densely. With acetylene, the cam has to be heated so high that controlling the flow of the rod is often difficult. It just runs all over. But we have to use acetylene on Honda cams because they have a form of graphite introduced into the lobes to alleviate the wear problems they used to have. Trying to hard-face over a lubricant like graphite is tough, but we now use a new rod which works very well. On the built-up cams, we grind a groove in the center which begins on the ramp, continues through the flank, up over the nose, and down the other side. The hard-face is then laid beginning in the center of the groove and is layered to a thickness of 1 /8 in. or so at the top of the nôse. Even after grinding, there is enough hard-face to keep from going into the original material, and with the groove full of the hard-face material, it doesn’t matter if you do grind a little below where the original material was. LIFTER DESIGN CW: What influences lifter design? We know that some machines use a radiused lifter, while others use a flat tappet, and a few use a roller tappet. Which is best, and why ? Norris: The lifter design is really an outgrowth of the engine’s design and the purpose for which the machine was originally designed. A roller tappet requires a larger base circle on the cam than a flat tappet with the same lift and duration characteristics, but is usually quieter in operation. A flat or radiused tappet can be made almost as silent through the use of quieting ramps on the cam lobe itself. A quieting ramp merely begins the lift pattern a little earlier and more gradually. With a racing engine, however, noise is of little consequence, and the most important considerations are to get the valve open as quickly as possible, hold it open a long time, and then get it closed. Media Credit Media Caption "Master" cams for the Norton (above) and Triumph (below). These devices are patterns for grinding a customer's cam and fit on the end of the cam grinding machine. Media Description Media Image Media Credit Media Caption Norris prefers double straight-wound valve springs with a third, flat-wound spring in between to cancel our harmonics. Media Description Media Image CW: Do you make any roller tappet conversions for the British and Japanese machines? Norris: No. We don’t feel that they’re necessary and they do have several disadvantages. First of all, they’re expensive, and they take up more room. The rollers also have a tendency to slide or skid over the lobe at high rpm, and the needle bearings inside the roller often fail under such conditions. They work well in large V-8 car engines because the cam lobes and roller diameters are large, but not in high-rpm motorcycle engines. The Triumph uses a radiused lifter that approximates a roller lifter’s shape, so we use a “roller profile” grind on the cam. CW: What about the ratio of the rocketarm on an overhead valve engine? Norris: Well, the ratio of the rocker arm is decided by the engine designer, and we haven’t found it necessary to change it on a motorcycle engine. If we want a valve lift of 0.400 in., and we know a rocker arm ratio is 1.2:1, we grind the cam to have a lift of 0.352 in. Most of our cams have higher lift and longer duration than our competitors’ cams, but we’ve been able to get good results because of other techniques we use. THE VALVE SPRING Norris: The valve spring’s function is to control positively the opening and closing of the valve. But the spring also has to force the valve, rocker arm, pushrod and tappet back into their relative positions after the cycle has completed itself so that another cycle can take place. But it’s not as simple as all that. At high rpm, stresses on the valve train are multiplied greatly, and therefore spring pressures are often as high as 400 psi when the valve is fully open. CW: We notice that you have a flat third spring between the inner and outer valve springs. Norris: Yes, it’s called a damper spring and it serves to reduce the harmonics that the valve springs set up during their operation at different rpm. The springs behave much like a quitar string in that they flex in the middle, setting up a harmonic vibration. This harmonic upsets the springs to such an extent that premature valve float often sets in, keeping the engine from developing its maximum power. And it can also cause damage to other components in the valve train. The idea of the damper, then, is to put in a stiff spring between the inner and outer valve springs which is coiled in the opposite direction. This damper actually touches the other springs when they begin to go into harmonics, and has a reverse effect, and a cancellation effect occurs. Any drag between the three springs is reduced to practically nothing shortly after the engine is started as they “lap” themselves in. Using this design, we can effectively use lower spring pressure for a given rpm limit. For example, all our springs are constant rate, but the pressure of the valve on its seat in a 050 Triumph is only 90 lb. I bis low pressure means less cam lobe wear, and eases the strain on all components. We use and believe in this, not because it’s something new, but because it works. I’ve had customers with both Nortons and Triumphs pick up 300-500 rpm just by changing to our springs. CW: You also advocate the use oj your titanium retainers with your cams? Norris: Yes, there is quite an advantage to using titanium for the retainers instead of steel or aluminum. Titanium is lighter than steel and almost as strong. Although aluminum is lighter than either of the other materials, it isn’t nearly as strong. Every ounce you can save in the valve train is worth its weight in gold. INTAKE AND EXHAUST TUNING CW: What about intake and exhaust tuning? Do you take that into consideration when designing a cam? Norris: Because we design cams for engines that are already in production, we know we have certain parameters within which we can work. We keep pretty close track of all our cams, and if we find that a certain type of intake or exhaust system works well, we publish it along with the cam’s specifications in our catalog. The only way to be really sure is to use a dynamometer. If it works on the dyno, it will work on the track. But actual track testing under racing conditions can further development. A subtle change to an intake or exhaust system can make a world of difference. Media Credit Media Caption 1) A standard Triumph 650 cam. 2) Grooves are ground into the lobes to accept the hard facing. 3) A cam which has been hard-faced, and is ready for grinding. 4) The finished product. Media Description Media Image http://bondiviewertest.azurewebsites.net/DataView/Article/CW?issueKey=19710601&articleKey=19710601068 So, back to the Norris SS for the V11, are there any owners who have tried?