[disclaimer] Thes next few state are VERY general generilazations and not the end all to cam science unfortuantly cam generalizations are very vague at best since there is a lot more involved then just one or 2 items like we have been discussing[/disclaimer]
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Now the lobe seperation, if I'm not mistaken , is tied to overlap and effects the RPM range of the cam?
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This statement is mostly true, for a cam with the same lift and duration specs a cam with a tighter lobe cylinder will generally prvide more cylinder pressure and create a lower rpm for peak power but it generally higher peak torque number BUT at the expense of making a very narrow power band while the cam with a wider lobe seperation will generally blead more cylinder pressure off but provide a much wider power band wiith typically a higer peak hp rating at a slightly higher rpm than one with a tighter lobe seperation. The problem with stating the above statement is that depending on combonation you make more power with one cam that has 110 centers but with different lift and/or duration than aother cam with say 112 centers. While we are talking a generalizations a cam with a tighter lobe seperation will promote higher cylinder pressures because of where the piston is when the valve actually closes..
Genreally what i like to do is on a low compression pump gas motor is run 110 to 112 centered cam. On a low compression race gas motor is run a 108 to 110 centered cam and on a high compression pump gas motor is run a 112 to 114 and on a high compression race gas motor run a 110 to 112. The above lobe center recommendations are a very rough guideline for NA and gearing the car after makin a cam selection. Which is a point we haven''t even really brought up yet is gearing.
Generaly speaking I like to pick a cam that matchs the rest of the motor combination so as to make the most usable power (My definiton of usable power) and then gear the car accordingly.