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No formulas that I know of other than what the cam mfg catalogs have. After absorbing as much info as possible, it still took about 10 or more different grinds to get a feel for what works. I must have changed the cam timing 50 times as well. I learned that I either like bigger cams, or cam mfgs like to be very conservative with their recommendations.
I like wider lobe centers because they still make power just as well, but idle/lowend and mileage are greatly improved. Intake centerline seems to be very important, spend the time to dial it in. I would set a 3.5” stroke crank at 110, a 3.75” at 108. Fast ramp speeds rock, look at the duration of the cam @ .006", .020", .050", .100", .200", .300" to get the real picture of what a cam is made of, two cams can have the same advertised specs but in reality be totally different. Duration #'s are far more important than lift, also high lift is very hard on the cam because you need much stronger springs to keep it together. Just enough spring pressure to do the job is best, and a well cut cam can use even less pressure than a generic cam.
Example, I use a Crower hyd cam with 525 lift and 248/252 @ .050 up to 7800rpm with a seat pressure of only about 100lbs. I also run .010" lash. The cam has very close intake/ex duration numbers because my ex flows very well, a typical head needs more ex duration. I live close to Crower so I get to stop by and look at their “Master Lobe List”, it shows all the lobes they’ve made with all the specs. You can pick which lobes you want and they’ll cut it, very cool….
Hope this helps in some way.
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