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Old 09-09-2016, 05:17 PM   #47
davepl
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Join Date: Aug 2006
Location: Redmond, WA
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Re: Idle vacuum - why only 10 inches?

Quote:
Originally Posted by toolboxchev View Post
I thought they are both supposed to have the same lobe separation.????

Anyone one this???
LSA is the distance between the peaks of the intake and exhaust - so you take the two of them and add them, divide by two, and that gives you the difference, which is the separation.

You can google "lobe separation angle" and get a similar description (below). Since a tighter LSA means the lobes are closer together, they overlap more. That's why a wider LSA gives you a better quality idle, but less power up top.

“The lobe separation angle is the angle in camshaft degrees between the maximum lift points, or centerlines, of the intake and exhaust lobes,” says Eric Bolander of Erson Cams. “It affects the amount of valve overlap; that is the brief period of time when both the intake and exhaust valves are open."
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