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Here is some more interesting background on heory. Especially the sensitivity numbers highlighted in Red below which would indicate the level of sensitivity to cam degreeing accuracy.
From a practical standpoint, if you want to degree a stock cam, that isall that matters. If you buy an aftermarket cam, it would be worth the money you spend to get it degreed to the closest degree as specificed by the manufacturer. If you are racing well you dot need my advice.
http://instructor.mstc.edu/instructor/candres/studentaccess/Presentations/Unit%204/Camshaft%20Theory%20and%20Design.ppt#256,1,Camshaf t Design and Theory
http://www.compcams.com/Technical/TimingTutorial/
http://www.hotbikeweb.com/tech/0711_hbkp_tech_tips_camshafts/final_thoughts.html
Changing Cam Timing: Retarding or advancing a cam 4-degrees will move the engine's power band either up (retarded) or down (advanced) approximately 300 to 400 rpm. Closing the intake valve later and/or opening the exhaust valve earlier tend to move the power band higher. Basically, retarding a cam increases top-end horsepower, while advancing a cam improves low-end torque. If power improves when the cam is retarded more than 4-degrees, the cam is too small and requires more duration. On the other hand, if power increases when the cam is advanced more than 4-degrees, the cam is too large and less duration would probably improve performance. All else being equal, a cam with a later closing intake valve requires an increased mechanical compression ratio to maintain a given low speed performance.
SAMPLE TWIN CAM CAMSHAFTS
Table 2 Valve lift with 1.625:1 rocker arm ratio. *Gear Drive, reverse rear cam rotation.Note the TW37s and TW37b cams have the same amount of duration and lift but the opening and closing valve timings are different, by changing the timing of the opening and closing events, Lobe Center, Lobe Separation Angle, and the amount of overlap change. Also note that duration values change when measured at different tappet lifts, such as .053" and .020". Accurate comparisons can only be made with measurements taken at the same tappet lift.
Here is some more interesting background on heory. Especially the sensitivity numbers highlighted in Red below which would indicate the level of sensitivity to cam degreeing accuracy.
From a practical standpoint, if you want to degree a stock cam, that isall that matters. If you buy an aftermarket cam, it would be worth the money you spend to get it degreed to the closest degree as specificed by the manufacturer. If you are racing well you dot need my advice.
http://instructor.mstc.edu/instructor/candres/studentaccess/Presentations/Unit%204/Camshaft%20Theory%20and%20Design.ppt#256,1,Camshaf t Design and Theory
http://www.compcams.com/Technical/TimingTutorial/
http://www.hotbikeweb.com/tech/0711_hbkp_tech_tips_camshafts/final_thoughts.html
Changing Cam Timing: Retarding or advancing a cam 4-degrees will move the engine's power band either up (retarded) or down (advanced) approximately 300 to 400 rpm. Closing the intake valve later and/or opening the exhaust valve earlier tend to move the power band higher. Basically, retarding a cam increases top-end horsepower, while advancing a cam improves low-end torque. If power improves when the cam is retarded more than 4-degrees, the cam is too small and requires more duration. On the other hand, if power increases when the cam is advanced more than 4-degrees, the cam is too large and less duration would probably improve performance. All else being equal, a cam with a later closing intake valve requires an increased mechanical compression ratio to maintain a given low speed performance.
SAMPLE TWIN CAM CAMSHAFTS
Table 2 Valve lift with 1.625:1 rocker arm ratio. *Gear Drive, reverse rear cam rotation.Note the TW37s and TW37b cams have the same amount of duration and lift but the opening and closing valve timings are different, by changing the timing of the opening and closing events, Lobe Center, Lobe Separation Angle, and the amount of overlap change. Also note that duration values change when measured at different tappet lifts, such as .053" and .020". Accurate comparisons can only be made with measurements taken at the same tappet lift.
with little $$$$ spent. 110 degrees I have found is optimum for power.
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