Those duration numbers can't be right. There's only 360 degrees in one rotation, leaving the valves closed for only 8-10 degrees!
-Dave
Cam duration is given in crankshaft degrees. The crank turns twice (720 deg) for every single revolution of the cam (2:1 ration on the timing gears). So it's possible to have more than 360 deg. of duration, although that's WAY too much for a stock cam (or any other--the most is usually in the low 300s). Duration can also be measured in different ways that will affect the numbers. I you measure at .002" of valve lift, you will have more duration than if you measure at .050" lift. That's why it's important when comparing numbers between cams that you use the same [EMAIL PROTECTED] figures. Comp Cams makes a Pro-Mod cam that has 360 deg advertised exhaust duration and is 320 deg @ .050 lift with .867 total lift, but you wouldn't run that in your street ride! I wonder if Larry accidently hit the 3 key instead of the 2 key.???
BL
