Originally Posted by techinspector1
This line of thinking may have been generated from the idea that gear drives will set up harmonics which are harmful to the valvetrain. Apparently, this has sound engineering basics, although I have never personally read of or talked to anyone who has experienced problems related to gear drives.
Some of these things get twisted around by the passing of information from one human to another. If you sit 10 people down in a row, whisper any statement to the first one and have the message be passed from one person to the other by whispering between them, the statement will be completely different when it gets to the 10th person.
So it is with the passing of technical information from one person to another. For instance, engineering techs at Blower Drive Service will tell us that a blower motor will operate best on gasoline using a camshaft with a LSA of 110 degrees and that the same motor on alcohol will operate best with a wider LSA of around 114. That has not kept the rumor at bay that ALL blower motors need a wide LSA, a bogus notion passed from one individual to another to another to another.
So maybe people are getting confused overlap and lsa because they do not always need to go hand in hand. A narow lsa cam can have little overlap with short duration and a wide lsa can have plenty overlap with lots duration.