MOTORCYCLE CAM DEGREEING FOR ZOMBIES

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1 MOTORCYCLE CAM DEGREEING FOR ZOMBIES Don t let the title deceive you into thinking this write up being a parody of sorts for all the information contained within is basically excerpts from the camshaft manufacturers themselves and experts alike. I have spoken with numerous individuals that have considerable more knowledge than I regarding the subject matter, such as Larry Cavanaugh (Cavanaugh Racing heads), Plummen (truly, special gratitude to Larry & Plum), Timebomb, Mark1122, Sandy and Kawasakiman as well as others to pick their minds. Basically I bugged the hell out of them until they gave me what I wanted to shut me up! Since Dummy s is copy righted, I had to come up with something different; henceforth Zombies seemed to work. And yes, before some of you get all wound up and defensive on me, I place myself into this category as well for I had no idea what this all meant. In my project (1976 KZ 900-A4) I chose to upgrade my camshafts using Web-Cam degree Valve Lift duration. These camshafts are depicted as a mild street performance cam for stock engines with a stock base circle, meaning as a drop in camshaft. So the calculations and measurements will be based on my CAM s, your readings may and will be different pending your cam s but the process should be the same regardless. Being new to this depth & realm of engine building, outside of drop in camshaft ; What exactly does all this mean to me and what am I supposed to do with this data? Oh crap is the first thing to mind! Drop in camshaft truly only means no valve cover or head machining/modification is required! Well, that is why I m writing this concise but condensed revision of How to Degree in your new aftermarket camshafts for Zombies like me! This will be a step by step approach with a lot of pictures and manufacturer images/text as well. As previously mentioned, all information within is from experienced individuals and from the camshaft manufacturers themselves. I also purchased a copy of Dale Walkers Step by Step Cam Degreeing for research and studying. Note: When you come across one of these, Zombie, this is your alert, so pay the attention to what is being depicted. What will be covered is as follows. Tools required such as degree wheel, TDC tool, Travel Dial Indicator, mounting hard ware etc Camshaft Specification Card: Calculations and measurements of the Camshafts, Lobes, Lift, Base Circle etc Step by Step Cam Degreeing process on a KZ-900 (903cc modified to 1015cc) engine. Tools required and locations where to purchase. Pg( 2 ) Camshaft Specification Card: Pg( 3 ) WebCam Camshaft Calculator: Pg( 4 ) Mounting the Dial indicator & Accurately Finding TDC (Degree Wheel & TDC Tool) Pg(5-8) MOST important part of Cam Degreeing!... Pg( 9 ) TDC & Cam Degreeing Step by Step Pg (10 13) Tips via Larry Cavanaugh. Boot in OMR s ass Pg(14) WebCam Degreeing in Cams Pg(15-17) Glossary for terminology Pg(18-22) Doug Meyers Cam Lobe Centers Explained Pg(23-25) All in all, after studying the information available on the web, speaking with others (actually bugging the hell out of Larry and Plummen), doing my research, in studying the hell out of it all and eventually going through the process myself, I realize now how easy it truly is and what a big sissy girl I was in thinking this was over my head. Ok, I was acting like a pussy! I hope this is helpful for others diving into the realm of Cam Degreeing. It s truly not that difficult! Yes you must pay attention to detail but in following these simple steps and taking your time, double/triple checking your measurements you will succeed. If I can do it, so can you! NOTE: I don t claim to be an expert in this matter, only a Zombie that was trying to make sense of it all and accomplish the task at hand, Degreeing in my CAMS! Dave OMR D Amato 1

2 Tools required and locations where to purchase: I bought my kit off Pit Stop Performance: $85.00 In researching these kits, I found some of the prices anywhere from $100-$300. Since this kit did include the APE degree wheel and TDC tool and for the fact that this isn t something I would be using everyday, $85 was reasonable. Gauge_W0QQitemZ QQcmdZViewItemQQptZMotorcycles_Parts_Accessories?_trksid=p4506.m20.l1116 schnitzracing: CIK-001 Cam Degreeing Kit $ CD-DVD DVD, Dale Walker Cam Degreeing $ Recommended for additional confidence! Hole Shot Performance: Complete Hole Shot Cam Degreeing Kit. Part No. CDK $ ea. Cam Degreeing video DVD. Part No. CDK-DVD $28.95 ea. Hole Shot degree wheel only. Part No. HP-1000 $18.95 ea. Pingel s: As can be reviewed, they vary in pricing but keep in mind; some of these kits also include a DVD, extra/different TDC tools, carrying case etc. Search the web and options best for you and your projects and wallet! Or via APE and other suppliers, piece together your own set. Just don t be cheap; buy quality tooling whatever you choose for this is an extremely important part of your motor. You spent all this time and $$$ putting into this old girl and now you want to go cheap. What is the matter with you! 2

3 Camshaft Specification Card: Regardless of the camshaft manufacturer, you should have received a timing/specification card with your camshafts. If not, you should be able to obtain off the manufacturers web site for your specific camshaft As depicted in the image below for my Web Cam camshafts,.365 Lift, Grind 118. This card contains important information you will be using in your setup, calculations and measurements. inches, lobe centers, intake and exhaust openings and closings are important to us at this time! If using Web Cam camshafts, follow the link for their calculator. I believe this will work with any camshaft or at least I don t see why it wouldn t Give it a shot! My camshaft calculator results. Note the overlap and installed Center Line = Lobe 105 degrees! 3

4 Let s compare the OEM KZ900 camshaft specifications card and try to understand a few things.. But first, please refer to Doug Meyers Cam Lobe Centers Explained on page 18. It truly is a wonderful explanation and there s just no way for me to try and explain it any better! OEM camshaft: WebCam.365 camshaft: Very generally speaking, the effect of moving lobe centers is as follows: Advancing the intake and retarding the exhaust ( closing up the centers ) increases overlap and should move the power up in the RPM range, usually at the sacrifice of bottom end power. The result would be lower numerical values on both intake and exhaust lobe centers. Retarding the intake and advancing the exhaust ( spreading the centers ) decreases overlap and should result in a wider power band at the sacrifice of some top end power. This condition would be indicated by higher numerical values on both intake and exhaust lobe centers. By moving only one cam the results are less predictable, but usually it is the intake that is moved to change power characteristics since small changes here seem to have a greater effect. With twin cam engines we have the luxury of moving the cams independently. As can be reviewed above in comparing the lobe center and over lap data, in the camshaft selection I choose, I m closing the lobe center gaps thus moving my power band into mid range where I want it. For my riding style, I don t require to be the fastest off the line so sacrificing bottom end power is not an issue. I want my power in low to mid range where we normally ride, meaning if doing 30-70mph, I hit that throttle for passing she s going to respond like a raped ape! What this boils down to where hopefully you ve gained a little more idea of how this all works, is as follows. Do your research before deciding on your camshaft, bigger is not always better depending on what you re looking for in response and operations. You want to be off the line first, you want upper rpm range increases, or like me, low to mid range response. Again, do your research! As provided by Larry Cavanaugh Thanks Larry! An easier Lobe Center Calculation to remember and as can be reviewed, comes out the same! Just subtract the smaller measurement from the larger measurement, add 180 and divide by 2. How can it be more simpler than that! Intake 18 Intake = = / 2 = 105 Lobe Center 4

5 Accurately Finding TDC (Degree Wheel & TDC Tool): The following are actual images during my project where the head was off so finding top dead center was a breeze for I can see the piston tops! With this in mind, I already have pistons 1 & 4 TDC (Top Dead Center). It s ok for we ll go through the process just the same. You must start the procedure with pistons 1 & 4 TDC! I also found that most articles and the Dale Walker DVD depicted the following. If you change/update your cam shafts (after market non OEM), timing belt/chain, tensioner, cut your head or deck your block, you must degree in your cams! I also found where the recommendation for adjustable cam sprockets was depicted. In my project I m using APE adjustable cam sprockets so I ll start here. The APE sprockets don t have the case alignment marks on them but use dimple indents versus arrows/triangles as in OEM sprockets. You will find intake or exhaust markings on them so make sure you have the correct sprocket on the correct camshaft. If using your OEM sprockets, please insure you have the correct sprocket on the appropriate cam shaft. With each cam orientated as depicted below, with one bolt only (top side for adjustment) snug the bolt center adjusting slot. See right image below. Accomplish this for both cams and follow your manual for camshaft installations. From your Kawasaki KZ900 Shop Manual (pg 30, 31 in my manual) or other manuals, follow the procedure for installing your camshafts into the head. I wouldn t be able to explain any easier than what is depicted or written in your manuals You should now have your cam shafts installed in the head to manual specifications, timing chain and tensioner in place, top idler assembly installed. All bolts torqued to specifications NOTE 1: Insure pistons 1&4 are roughly TDC (Top Dead Center). Peak through spark plug hole #1 cylinder. NOTE 2: Disconnect Battery: All crankshaft rotation is by manual means! NOTE 3: Cam Sprockets, 1 cam bolt per sprocket positioned in the center of the sprocket slot (right image above). NOTE 4: Camshafts, cam sprockets, cam adjuster installed and torqued to OEM specifications! Read the Web-Cam procedure Pages (15-17). For the most part, it s the same exact thing as being depicted below! 5

6 Mounting the Dial indicator: We ll first start with the Intake Cam NOTE: This will also be required on the exhaust cam! 1) Cut a 1/8 steel plate for the dials magnetic mounting block and bolt down to the head where the valve cover bolt holes are mated. Install on left side of engine for cylinder # 1. NOTE: This procedure can also be accomplished using cylinder # 4, on the right side of the bike. But this is how I did mine as for following the DVD and other data I found. 2) Curved dial extension. I made mine out of coat hanger wire Hammer down the tip for nice flat surface on shim face and for decreasing the thickness for the small dial indicator screw, acts as a washer of sorts You ll need to play around with the bends a little so the tool does not hit the cam lobes, cam base circle or tappet side walls when in place during camshaft rotations (valve fully open or fully closed) This is the one I used This one was recommended from others 6

7 3) Parallel with the valve and perpendicular with the bucket. Basically meaning you want the tool to fully follow the same rise and fall as your valve FULL movements. NOTE: Rotate the crank shaft while observing the dial arm rise and fall. You want the tip to follow with NO obstructions whatsoever! Rotate several times 360 degrees of the camshafts Insure the cam lobe does not hit the extension arm This is a must for accuracies so take your damn time, triple check/confirm through out a full 360 degree cam shaft rotation and insure this is so! 7

8 Installing the Degree Wheel: Outer nut wrench size: 17mm for rotating the crankshaft during this procedure! NOTE: Do not wrench on the smaller inside 13mm nut or damage may occur! Nor do we rotate the crankshaft via the alternator nut due to reverse threads! Some say otherwise, your call Remove ignition plate (right side of engine) for crankshaft degree wheel installation and crankshaft rotations. NOTE: You may have to grind the TDC tool tip side walls (NOT the tip height!) due to hitting the valves. Rotate the cams forward where the exhaust valve is 80-90% open. Try to insert and thread the tool. If it hits the valve you ll know it! 8

9 Here's the things I learned that are the MOST important part of Cam Degreeing!... Dial indicator: Again, SETUP is the most crucial! Take your time, with the dial setup, manual rotate slow with smooth rotations (not jerky) the cam 360 degrees, insure the dial reacts/follows without obstructions, insure it comes back to 0 TDC on the dial indicator... Double/triple check for obstructions during rotations before even attempting any adjustments. Dial zeroing: I was chasing the dial indicator all over the place, gave me inaccurate recordings... So what I do now is this and works out every time... After the first dial zeroing (dial outer lens rotation to 0 degrees)... Example: Do the procedure for measurements/calculations and make my sprocket adjustment, rotate forward to TDC... The dial indicator at TDC may or may not be on the spot 0 TDC. I rotate twice forward (crank 360 degrees rotation) back to TDC for dial = 0 TDC thus insuring it is TDC 0 degrees! TDC Tool: You must grind down the thickness (not height!) of the TDC tool for as you manually rotate the cams, the valves will most likely (99.9% positive) hit the TDC tool. While looking through spark plug hole # 1... Rotate the camshaft forward until the exhaust valve is almost fully open. Not true TDC yet where the piston is fully up!. Try to insert and fully thread in the TDC tool. If it hits the valve, grind a little more off the TDC tool side wall. Again, NOT the tip height!!!! Which.050" to use in your calculations! First.050" to use: On the cam lobe opening side, the first measurement for calculations will be the first.050" the dial comes too. Meaning the first.050" as the valve is just beginning to open for the degree wheel measurement. Second.050" to use: Each cam shaft due to lobe height will be different for the number of turns of.050" As the crank is rotated forward, the dial indicator will sweep counter clockwise. As it hits the lobe TDC, the dial will stop and reverse direction as your now on the back side of the lobe. Depending on the lobe height, you want the last.050" of the dial just before the valve fully closes for the degree wheel measurement. 9

10 1) The degree wheel and pointer is 0 degrees, pistons 1 & 4 are TDC. 2) Find Accurate TDC using the Positive Stop method with TDC tool: NOTE: For all rotations, go SLOW! You don t want the piston being damaged via the TDC tool contact! 2.1) Rotate the crank shaft forward (direction of operation, rotate towards front) degrees and install the TDC tool (manufacturer specifications) in cylinder/piston # ) Slowly rotate the crankshaft backwards (opposite direction of operation, rotate towards rear) until the piston contacts the TDC tool and record degree 53 degrees in my case! 2.3) Slowly rotate the crank shaft forward ~ 270 degrees until the piston contacts the TDC tool and record degree 34 degrees in my case! NOTE: The recordings depicted are from my.365 cams and measurements. Yours may be different! Math: 1 st reading/recording: 53 degrees 2nd reading/recording: + 34 degrees 87 degrees Divide by 2: 87 / 2 = 43.5 degrees = Accurate Top Dead Center Reference Point! 2.4) Relocate the pointer tip (NOT THE DEGREE WHEEL) to 43.5 degrees as TDC Reference Point. 2.5) Rotate the crankshaft backwards in the opposite direction of running (~ 360 degrees) until the piston makes contact with the TDC tool. This should end up at 43.5 degrees on the degree wheel indicating the intake cam is opened with the lobe pointing backwards. NOTE: If this does not end up correctly (43.5 degrees), you messed up somewhere, start over! 2.6) Remove the TDC Tool and rotate the crankshaft forward to 0 degrees on the degree wheel. NOTE: Rotate once again a full camshaft 360 degree rotation insuring the dial indicator is truly back to 0 degrees! Then rotate the crankshaft again for another 360 degrees for confidence, it should be dead nut back at 0 degrees on the dial indicator! NOTE 2: As previously mentioned, don t jerk the crank around! Rotate the crank with steady even pulls of the 17mm wrench. Also insure your degree wheel is moving on you Every couple of rotations or so, when back at TDC 0, I hold the wheel in place and insure the 13mm nut is snug. Don t over tighten for you ll snap this bolt and you ll be in bad shape! And for God s sake, take your time! You are not part of a pit crew and you don t get any ata boy s for accomplishing this quickly! 10

11 3) Degreeing in the Cams: 3.1) Camshafts (mine) are manufactured with a lobe center of 105 degrees. 3.2) Rotate the crankshaft forward until heel of cam makes contact with shim. 3.3) Zero in your dial indicator. NOTE: Do not touch/hit your degree wheel or pointer from here on out or you MUST start over! NOTE 2: Do not back up the crankshaft! If you pass the marking, go all the way around! 3.4) Rotate the crankshaft forward until the dial indicator is at.050 of an inch! This equates to the FIRST.050 as the valve is starting to open! 3.5) Record Degree Wheel Marking! Example mine is at 54.5 degrees. 3.6) Rotate the crankshaft forward until last.050 of an inch is measured as intake valve closes. This equates to the last.050 of valve just before fully closed! 3.7) Record Degree Wheel Marking! Example mine is at 23.5 degrees. You will find a whole slew of different formulas to calculate such as add the two recordings together, add 180, then subtract one of the numbers pending intake or exhaust blah-blah-blah. Here s the easiest formula I found and it comes out 100% the same, regardless if Intake or exhaust, works the same for both measurements and calculations. Subtract the smaller of the two recorded numbers from the bigger recording number. Divide that subtraction total by 2. Add 90 degrees. Math: 1 st reading/recording: 54.5 degrees 2nd reading/recording: degrees / 2 = degree Measured Lobe Center I got lucky, should be close enough especially considering throughout the break in period this cam chain will stretch a little but I want mine at 105 Lobe Centers, not So what now! Intake Cam: Since the lobe center calculated at degrees, this number is larger than the specification sheet of 105 degrees; we need to rotate the crankshaft backwards opposite of direction of running. If the number had been smaller than 105 degrees, we then would rotate the crankshaft forward in the direction of running operation a few degrees. Loosen the INTAKE cam sprocket bolt and rotate the camshaft backward a few degrees (~1/16 th to 1/8 or 1-4mm) and then tighten snug the cam sprocket bolt and go through the procedure from TDC 0 once again (REMEMBER, TDC 0 A COUPLE TIMES) and re-check your measurements for the desired Measured Lobe Center 1 st reading/recording: 54 degrees 2nd reading/recording: - 24 degrees 30 YEAH BABY DIALED INTO PERFECTION!!! 30 / 2 = degree Measured Lobe Center 11

12 At which point, add Loctite to your remaining exhaust bolts and insert one at a time and torque down to 11 to 12 ft lbs. Rotate the crank around to the bolt you have been using for the degreeing process, remove and add Loctite and torque down. Now just for shits and giggles, rotate back to TDC 0 a couple of times insuring the dial indicator is at 0, go through the process and you should record, measure and calculate back at 105 degree Measured Lobe Center! Exhaust side: Pretty much the same procedure Rotate the crankshaft forward until heel of cam makes contact with shim. 3.8) Rotate the crankshaft back to zero degrees TDC. 3.9) Relocate the dial indicator over to the exhaust valve, #1 cylinder. 3.3) Zero in your dial indicator. NOTE: Do not touch/hit your degree wheel or pointer from here on out or you MUST start over! NOTE 2: Do not back up the crankshaft! If you pass the marking, go all the way around! 3.4) Rotate the crankshaft forward until the dial indicator is at.050 of an inch! This equates to the valve starting to open! This is the FIRST.050 you come across 3.5) Record Degree Wheel Marking! Example mine is at 40.5 degrees. 3.6) Rotate the crankshaft forward until intake valve of an inch. This equates to the valve just starting to close! This is the last.050 you come across 3.7) Record Degree Wheel Marking! Example mine is at 16 degrees. 1 st reading/recording: 40.5 degrees 2nd reading/recording: - 16 degrees / 2 = degree Measured Lobe Center Remember, my ideal configuration/specifications for my Camshafts is 105 Lobe center. Well you say. I m at degrees, lower than the desired 105 lobe center, now what? 12

13 Exhaust Cam: It s opposite the direction for the crankshaft rotations versus the intake side. If the lobe center calculated at a number larger than the specification sheet of 105 degrees; we need to rotate the crankshaft forward in the direction of running. Since the number is smaller than , we then rotate the crankshaft backwards opposite direction of running operation a few degrees. Loosen the EXHAUST cam sprocket bolt and rotate the camshaft backward a few degrees (~1/16 th to 1/8 or 1-4mm) and then tighten snug the cam sprocket bolt and go through the procedure from TDC 0 once again (REMEMBER, TDC 0 A COUPLE TIMES) and re-check your measurements for the desired Measured Lobe Center 1 st reading/recording: 44 degrees 2nd reading/recording: - 14 degrees 30 YEAH BABY DIALED INTO PERFECTION twice yet!!! Go Figure!!! 30 / 2 = degree Measured Lobe Center At which point, add Loctite to your remaining exhaust bolts and insert one at a time and torque down to 11 to 12 ft lbs. Rotate the crank around to the bolt you have been using for the degreeing process, remove and add Loctite and torque down. Now rotate back to TDC 0 a couple of times insuring the dial indicator is at 0, go through the process and you should record, measure and calculate back at 105 degree Measured Lobe Center! NOW::::: This is very IMPORTANT!!!! Stop what you re doing, go get a beer and yell out a big loud WHOYA!!!! Congratulations, you just degreed in your new camshafts to specified lobe centers.. See, I told you it wasn t that hard (Yeah sure) hahahahahaha. Now, all joking aside, after a break in period, say 500 to 1000 miles, go through and re-dial these babies in after the cam chain has gone through it s break in period and has stretched a little. Congratulations ZOMBIE, you just degreed in your Cams! 13

14 Via Larry Cavanaugh, Thanks Brother! You're late in your valve timing. It's a higher lobe center. You are 4 degrees late on your open and close points. You need to advance the cam 4 degrees. YOU NEED TO BACK THE CRANKSHAFT UP WITHOUT MOVING THE CAM. Now, let's look at what is required when you need to change the lobe center of the cams. Let's do the Intake cam first. Suppose your required lobe center is a 105. Say you've checked your open and close points...crunched the numbers and you have a 109 lobe center. Where are you in terms of timing? You're late in your valve timing. It's a higher lobe center. You are 4 degrees late on your open and close points. You need to advance the cam 4 degrees. What do you need to do in terms of moving the crankshaft? Picture this in your mind. The cam is open to your.050" checking lift. Timing card says that you should be 18 degrees BTDC when the valve is open.050" but your degree wheel says you are at 14 degrees BTDC. Now, look at what your degree wheel reads. Note the number. Loosen the cam sprocket bolt. Rotate the crankshaft counterclock wise [viewing engine from ignition side] and carefully move the crankshaft backward 4 degrees. While you're doing that, also watch the cam to be sure it's not moving. The cam should remain still... This is where the adjustable sprockets come in to dial in the required 4 degree difference for obtaining the specified 105 degrees! 14

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18 Glossary for Terminology: NOTE: This was copied of WebCams website! The following information is provided to help you understand some of the terminology related to camshaft specifications, and information. 1. Max Lift or Nose 2. Flank 3. Opening Clearance Ramp 4. Closing Clearance Ramp 5. Base Circle 6. Exhaust Opening Timing Figure 7. Exhaust Closing Timing Figure 8. Intake Opening Timing Figure 9. Intake Closing Timing Figure 10. Lobe Separation ABDC After Bottom Dead Center. Measured in degrees. ASYMMETRICAL Not identical on both sides of the lobe. In most cases, the opening side of the lobe being much more aggressive than the closing side. This difference is only visible in some overhead cams. ATDC After Top Dead Center. Measured in degrees. BASE CIRCLE The concentric or round portion of the cam lobe where the valve lash adjustments are made. A high spot in this area is called BASE CIRCLE RUNOUT. BBDC Before Bottom Dead Center. Measured in degrees. BILLETS The blank shafts that the camshafts are made from. BTDC Before Top Dead Center. Measured in degrees. CAM FOLLOWER / TAPPET Usually a flat faced or roller companion to the camshaft that transfers the action of the camshaft to the rest of the valve train by sliding or rolling on the cam lobe. CAM LIFT This is the maximum distance that the cam pushes the follower when the valve is open. This is different from valve lift. See Gross Valve Lift. CAM LOBE The parts of the camshaft that create the valve movement. CAM MASTER Design of the cam transferred to a template or master. The master is then installed in the cam grinding machine to generate the shape of the lobes of the production cam. CAM PROFILE The actual shape of the camshaft lobe. 18

19 CAMSHAFT A shaft containing many cams that covert rotary motion to reciprocating (lifting) motion. For every 2 revolutions of the crankshaft, the camshaft rotates 1 revolution. The lobes on the camshaft actuate the valve train in relation to the piston movement in an internal combustion engine. The camshaft determines when the valves open and close, how long they stay open and how far they open. CARBURIZING Gas carburizing is a method to heat treat steel camshaft billets. In this method, the camshaft is placed in a carbon gas atmosphere furnace and heated to the proper temperature. When the shaft has absorbed the proper amount of carbon, it is removed from the furnace and quenched (cooled in oil) to the proper temper. CAST BILLET A term used to describe a camshaft which is made from a casting. The material for the casting is a special grade of iron alloy called "Proferal." CHEATER CAMS See Improved Stock Cams. CHILLED IRON LIFTER A cam follower made from high quality iron alloy that is heat treated by pouring the molten iron into a mold with a chilled steel plate at the bottom to heat treat the face of the lifter. It is compatible with steel and hardface overlay cams only. CLEARANCE RAMPS The portion of the cam lobe adjacent to the base circle which lifts at a constant slow speed. It's purpose, is to compensate for small deflections and take up the slack in the valve train created by the valve lash. The opening ramp takes up all clearances in the valve train and causes the valve to be on the verge of opening. The closing ramp begins when the valve touches the valve seat and ends when the tappet returns to the base circle. Ramp designs have a tremendous effect on power output and valve train reliability. COIL BIND A valve spring that has been compressed to the point where the coils are stacked solid and there is no space left between the coils. The valve cannot open any further when this happens. CONCENTRIC Running true or having the same center. In camshaft terminology, the cam bearings and lobes are concentric to each other when the cam is straight and there is.001" or less run out between all the cam lobes and bearings. CORE DIAMETER The diameter of the camshaft measured between the cam lobes. DEGREEING YOUR CAMSHAFT Degreeing In Your Camshaft means synchronizing the camshaft's position with the crankshaft. A few degrees of misalignment can affect the engine's operation dramatically. DOHC Double OverHead Cam. A pair of overhead camshafts, one to operate the intake valves and the other to operate the exhaust valves. DUAL PATTERN A camshaft having different grinds on the intake and exhaust lobes. There are various opinions on whether or not there is an increase in performance over a single pattern camshaft. Unfortunately there is no fair way to compare the two styles. Both types work quite well and there is no benefit to turning down one style of camshaft in favor of the other on this basis alone. DURATION The length of time that the valve is held off the seat by the cam. This is measured by the degrees that the crankshaft rotates. More degrees of duration will make the engine operate in a higher rpm range. DURATION AT.050" The distance measured in degrees of crankshaft rotation from when the valve is open.050" far until it is.050" from closing. FLAME HARDENING A heat treating process whereby a camshaft is exposed to an open flame and then quenched (cooled in oil). FLANKS The sides of the cam lobe or the portion of the lobe that lies between the nose and the base circle on either side. They are also called the opening and closing ramps. 19

20 GROSS VALVE LIFT This is obtained by multiplying the cam lift by the rocker arm ratio. Rocker arm production tolerances can vary this figure by as much as +/-.015". HARDENING Achieved by heating the material and quenching it in oil to give durability. Flame hardening and Induction hardening are two methods used. HARDENABLE IRON LIFTERS A cam follower made from high quality iron alloy. This special alloy is compatible with cast iron billet camshafts. The entire body of the hardenable iron lifter is hard as compared to the chilled iron lifter where only the base is hardened. HYDRAULIC VALVE LIFTERS These lifters are designed to maintain zero lash in the valve train mechanism by use the engine's oiling system to automatically adjust the valve lash (clearance) to zero. Hydraulic lifters do maintain a constant pressure on the camshaft lobe, which solid lifters do not. Their advantages include quieter engine operation and elimination of the periodic adjustment required to maintain proper lash as with solid valve lifters. IMPROVED STOCK CAMS (CHEATER CAMS) The improved stock cam has stock lift and duration but the flanks are modified so that they are faster acting. This process adds about a 5% increase in the area under the lift curve. This means there will be a power increase during the entire rpm range of the engine. This type of grind works very well in engines that have fuel injection systems that run off of manifold vacuum and are therefore very sensitive to camshaft duration changes. LOBE The lobe is eccentric to the cam bearings of the camshaft and transmits a lifting motion through the valve train to operate the valves. The design of the lobe determines the usage of the camshaft. (i.e. street use or all out competition). LOBE AREA Used for comparison only. The figure is obtained by adding the lift at every degree of rotation. LOBE CENTERS The distance measured in degrees between the centerline of the intake lobe and the centerline of the exhaust lobe in the same cylinder. LOBE CENTERLINES-VALVE The point at which the valve is fully open. For example, full intake lobe lift at 110 deg. ATDC. full exhaust lobe lift at 110 deg. BTDC. This camshaft was ground with 110 deg. lobe centers and is timed straight up. It is neither advanced or retarded. Another example, full intake lobe lift at 105 deg. ATDC. full exhaust lobe lift at 115 deg. BTDC. This camshaft was ground also on 110 deg. lobe centers but is advanced 5 crankshaft degrees. LOBE TAPER This is the amount by which the diameter of the front of the base circle is different from the diameter of the rear of the base circle. The amount of taper can be anywhere from zero to.003" depending on the engine. If the forward side of lobe is greater than the rear side we say that the cam has taper left (TL). If the back side of the lobe is greater than the front side then we say that the cam has taper right (TR). Lobe taper has a dramatic effect on the speed of rotation of the lifter. If the lifter does not rotate at the proper speed, premature lifter and cam wear will occur. NET VALVE LIFT The actual lift of the valve. This lift can be determined by subtracting the valve lash dimension from the gross valve lift figure. Rocker arm production tolerances can vary this figure by much as +/-.015". NITRIDING Gas nitriding is a surface heat treatment which leaves a hard case on the surface of the cam. This hard case is typically twice the hardness of the core material up to.010" deep. This process is accomplished by placing the cam into a sealed chamber that is heated to approximately 950 degrees F and filled with ammonia gas. At this temperature a chemical reaction occurs between the ammonia and the cam metal to form ferrous nitride on the surface of the cam. During this reaction, diffusion of the ferrous-nitride into the cam occurs which leads to the approximate.010" case depth. The ferrous-nitride is a ceramic compound which accounts for its hardness. It also has some lubricity when sliding against other parts. The nitriding process raises and lowers the chamber temperature slowly so that the cam is not thermally shocked. Because of its low heat treat temperature no loss of core hardness is seen. Gas nitriding was originally conceived where sliding motion between two parts takes place repeatedly so is therefore directly applicable to solving camshaft wear problems. NOSE OF THE LOBE The highest portion of the cam lobe from the base circle with the highest lift. 20

21 OHC Overhead Cam Engine. A camshaft in an automotive engine that is located in the cylinder head over the engine block rather than in the block. OHV Overhead Valve Engines. In this type of engine the camshaft is positioned beneath the valves. OVERLAP A situation where both the intake and exhaust valves are open at the same time when the piston is at top dead center on the exhaust stroke. The greater the seat duration is on the intake and exhaust lobes, the greater the overlap will be in degrees. PARKERIZING A thermo-chemical application whereby a nonmetallic, oil-absorptive coating is applied to the outside surface of the camshaft. This protects the cam lobes during the break-in period. PRELOAD The type of adjustment for hydraulic lifters. When the clearance is removed from the valve train the rocker arms, or adjustable pushrods, are tightened an additional turn to "preload" the hydraulic lifter. RATE OF LIFT The speed that the valve opens and closes. Cams with a higher rate of lift have more lobe area to provide performance gains. Also known as ramp rate. REFINISHING Restoring the cam lobe to its original shape (except slightly smaller) when there is only minimal wear. ROLLER TAPPET The roller tappet performs the same function as the mechanical or hydraulic tappet. However, instead of sliding on the cam face, the lifter contains a roller bearing which rolls over the cam surface. SEAT DURATION The total time in degrees of crankshaft rotation that the valve is off of its valve seat from when it opens until when it closes. SPLIT OVERLAP An occurrence when both the intake valve and the exhaust valve are off their seats at the same time by the same amount. SPRING FATIGUE Valve springs have a tendency to lose their tension after being run in an engine for certain periods of time, because of the tremendous stress they are under. At 6,000 rpm, for example, each spring must cycle 50 times per second. The tremendous heat generated by this stress eventually effects the heat-treating of the spring wire and causes the springs to take a slight drop in pressure. SPRING SURGE The factor which causes unpredictable valve spring behavior at high reciprocating frequencies. It's caused by the inerita effect of the individual coils of the valve spring. At certain critical engine speeds, the vibrations caused by the cam movement excite the natural frequency characteristics of the valve spring and this surge effect substantially reduces the available static spring load. In other words, these inertia forces oppose the valve spring tension at critical speeds. VALVE FLOAT When the speed of the engine is too great for the valve springs to control the valve. The valves will stay open and/or "bounce" on their seats. The clearance in the valve train created by valve float will also cause hydraulic lifters to "pumpup" as they try to eliminate the valve clearance. VALVE LASH This is the clearance between the base circle of the camshaft lobe and the camshaft follower or tappet. VALVE TRAIN The "train" of parts leading from the cam lobe to the valve. 21

22 VARYING LOBE SEPARATION ANGLE Tighten Widen Moves Torque to Lower RPM Raise Torque to Higher RPM Increases Maximum Torque Reduces Maximum Torque Narrow Powerband Broadens Power Band Builds Higher Cylinder Pressure Reduce Maximum Cylinder Pressure Increase Chance of Engine Knock Decrease Chance of Engine Knock Increase Cranking Compression Decrease Cranking Compression Increase Effective Compression Decrease Effective Compression Idle Vacuum is Reduced Idle Vacuum is Increased Idle Quality Suffers Idle Quality Improves Open Valve-Overlap Increases Open Valve-Overlap Decreases Closed Valve-Overlap Increases Closed Valve-Overlap Decreases Natural EGR Effect Increases Natural EGR Effect is Reduced Decreases Piston-to-Valve Clearance Increases Piston-to-Valve Clearance LOBE SEPARATION ANGLE Above 114 Deg. = Extremely Wide Deg. = Wide Deg. = Moderately Wide Deg. = Moderate Deg. = Moderately Tight Deg. = Tight Below 104 Deg. = Extremely Tight ADVANCING / RETARDING CAM TIMING ADVANCING Begins Intake Event Sooner Open Intake Valve Sooner Builds More Low-End Torque Decrease Piston-Intake Valve Clearance Increase Piston-Exhaust Valve Clearance RETARDING Delays Intake Event Closes Intake Keeps Intake Valve Open Later Builds More High-End Power Increase Piston-Intake Valve Clearance Decrease Piston-Exhaust Valve Clearance 22

23 One of the least understood topics and regarding engine tuning and building continues to be the concept of cam timing and lobe centers. The opening and closing process of an inlet or exhaust valve as controlled by a cam lobe constitutes a complete event in the cycle of the engine. Like any event, it has a beginning and an end. Naturally, then it also has a middle or center. The location of this center in relation to the rotational position of the crankshaft is known as the lobe center. The process of Degreeing cams allows the engine builder to place the lobe center of a cam in the correct orientation with reference to the crankshaft. The opening and closing points and resultant figures of the cam, although important, are very difficult to reference to set cam timing and are, after all, the result of where the lobe center is placed. Therefore the lobe center is used to reference cam timing. The difficulty in measuring the opening and closing points is the result of the very shallow and gradual starting and stopping of the valve motion. How do you tell just when the valve motion starts and stops? If you pick a specific amount of lift at some height beyond the initial gradual motion and always use that amount as a marker for the beginning and end of the motion, the center will always be halfway between these points. Therefore, the lobe center is computed from a timing number derived at a specific valve lift. Any lift could be used to compute this, but in the Japanese motorcycle industry 1mm or.040 is traditional. U.S. (automotive) cam grinders have used.050. This checking height must be used to minimize the effect of the shallow opening and closing ramps on the cam lobe. Without this, each builder s subjective notion of when movement starts would be the defining factor of timing. One picture is worth a few thousand of my words so now refer to my crudely drawn diagram for clarification. The diagram graphically shows how these points lie in relation to the degrees of crankshaft rotation. The usable range of lobe center values for just about all commonly used engines is only about 15 degrees wide from about 98 to 112 degrees and for the engines we use, the right spread is even smaller than that. Small changes of one degree can have considerable effect on the power delivery characteristics of an engine. Very generally speaking, the effect of moving lobe centers is as follows: Advancing the intake and retarding the exhaust ( closing up the centers ) increases overlap and should move the power up in the RPM range, usually at the sacrifice of bottom end power. The result would be lower numerical values on both intake and exhaust lobe centers. 23

24 Retarding the intake and advancing the exhaust ( spreading the centers ) decreases overlap and should result in a wider power band at the sacrifice of some top end power. This condition would be indicated by higher numerical values on both intake and exhaust lobe centers. By moving only one cam the results are less predictable, but usually it is the intake that is moved to change power characteristics since small changes here seem to have a greater effect. With twin cam engines we have the luxury of moving the cams independently. With a single cam engines you must advance or retard the intake and exhaust together, usually using the intake lobe center as the reference and only the cam grinder can spread or close up the centers when the cam is ground. Basically, here s how it s done in the real world. I m not going to tell you what lobe centers to use, as this varies from engine to engine, just how to determine them. Many engine builders take lobe center measurements with zero valve lash (clearance) so that all movement can be detected. In fact, the valve lash can actually be slightly negative, that is the valve can be held slightly open by the cam with the valve in the closed position. You may also do the calculation with the running clearance at the valve. The amount of pre-load or clearance on the valve has no effect on the lobe center number but will effect the opening and closing numbers. What IS important is that, for future comparison purposes, you always do it the same way with the same lash value. It is also very important that an accurate top dead center TDC reference be used when degreeing cams. Therefore, this should be checked carefully and the degree wheel and pointer set accordingly. Take a great deal of care when setting up your degree wheel, pointer, method of turning the engine, and dial indicator. A change of one degree can be significant, so accuracy is very important. A dial indicator is used to measure the valve motion in hundredths of a millimeter or thousandths of an inch. Set your dial indicator so that the plunger pushes on the retainer or tappet and moves as nearly parallel to the valve travel as possible. It is not necessary to use any particular valve, use one that allows the easiest indicator set-up and that you can easily see from the same side as the degree wheel. I recommend that you begin with the intake cam, since the intake is the most likely to be damaged by an insufficient amount of valve to piston clearance or incorrect timing. Always start with the cam sprockets closest to the stock position. Begin with the valve fully closed and with the dial indicator zeroed. Double check the plunger movement to see that it moves freely, does not interfere with the cam lobe, rocker, or any other moving parts, and returns to zero when moved and released. Rotate the engine in the correct direction while watching the dial indicator. Stop when the pointer shows 1mm of movement. Note this number. On an intake cam, this will be a value before top dead center (BTDC). Continue rotating the engine, watching the dial indicator as the valve opens, then begins closing again. By counting the revolutions of the pointer and watching it return towards zero, you can stop when the valve lift is still 1mm before fully seated, noting the degree wheel value at this point. On the intake cam this will be a value after bottom dead center (ABDC). It is important to stop at the correct point because you should avoid turning the engine backwards as this unloads the cam chain and can result in an erroneous reading. 24

25 To compute the lobe center, you: A. Add the two opening and closing numbers noted B. Add 180 to this sum C. Divide this sum by 2 D. Subtract the smaller number of the two opening and closing numbers from this quotient. The result is the lobe center. For Example: Intake opens (at 1mm lift) 38 BTDC Intake closes (at 1mm lift) 68 ABDC =286, divide by 2 =143, subtract 38 from 143 = 105 The lobe center on this cam is 105 degrees. The method is the same on the exhaust except the opening number will be a value before bottom dead center (BBDC), the closing value will be after top dead center (ATDC) and again, subtract the smaller number. For Example: Exhaust opens (at 1mm lift) 60 BBDC Exhaust closes (at 1mm lift) 40 ATDC =280, divide by 2=140, subtract 40 from 140 =100 The lobe center on this cam is 100 degrees. Note that in both cases, it is the smaller of the two numbers that is subtracted. Also note that the 286 and 280 degree values are similar to what may be the advertised duration of the cam. This number is called the checking duration as it is dependent upon the checking height used (in this case 1mm). Remember, the opening and closing values (and duration) are dependent on the checking clearance and will vary based on this amount. The lobe center number will not. This is why published numbers are not a good way to compare cams. You must always know the checking height that was used to derive those numbers. To change the lobe center, loosen the sprocket attach bolts and move the crankshaft slightly to alter it s relationship to the cam. Retighten the bolts and re-check. When the selected value is finally reached, tighten and loctite the bolts, then re-check one more time. With a little experience you will know which way to go to advance or retard a cam to achieve the desired lobe center. Caution: Moving lobe centers can drastically alter valve to piston clearance. And remember, the closest point is rarely at TDC. The most critical is the intake and usually occurs somewhere after TDC. Make all adjustments in small increments and NEVER force the engine past any resistance until you know the cause. Changes to the power output are can be subtle, hard to predict, and frankly, most of this has been explored to death so it s unlikely you will find some new power. But each engine is different and cam timing must be part of any fully prepared engine. Be careful with following we always did it that way thinking. The advent of electronic fuel injection and four valve heads has changed the cam requirements of engines. Increased valve area means less cam gives you more flow. On an injected engine you no longer need to create a strong vacuum signal through a carburetor throat for good fuel atomization. The injector is going to get the fuel in there instead of flow across a jet. The only way to optimize cam lobe centers is through extensive and careful dyno or performance testing. 25

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