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I'm wondering if I could get a good explanation as to why a larger diameter lifter, can get more lift than a smaller diameter lifter, everything else being equal. I have read about this in a few different articles, but no one has explained the mechanical reason as to why this happens. Thanks for the help. Mark
 

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I'm wondering if I could get a good explanation as to why a larger diameter lifter, can get more lift than a smaller diameter lifter, everything else being equal. I have read about this in a few different articles, but no one has explained the mechanical reason as to why this happens. Thanks for the help. Mark
here ya go Mark
very good info on this subject, Itll be easier to read then explain


http://tru-442.tripod.com/camselect.htm
 

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It's all about geometry and leverage. As the lift rate for each degree of rotation goes up, you get to a point where the point of contact between the cam and lifter is on the edge of the lifter. If that was ever allowed to happen, the lifter edge would act as a scraper and the lifter or cam would fail. If the lifter is bigger in diameter, you can have more aggressive cam action before the contact goes all the way to the edge.

A roller cam can take that one step farther because it can be ground with a reverse curve and still make proper lobe to roller contact. Years ago, one of the popular drag racing roller cams for a small block was called the "peanut cam" by all the racers - because the intake lobes were shaped like a peanut.
 
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