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what does lobe center/lobe separation mean in terms of cams? I am unfamiliar with what this actually means on the cam card...also, my cam card doesnt seem to refer to this "stat"...does it go by any other name?-Gus

There are several terms used to describe the specs of a cam. These measurments determine the performance of the cam ie. torque, RPM range, HP. Lift seams to be self-explanatory, it is the total amount the valve is lifted off the vavle seat. Duration has the greatest effect on the performance of the engine. The amount of duration determines where the engines powerband will be, and it has a direct effect on issues as idle quality and manifold vacuum. Duration is the amount of time (expressed in crackshaft degrees of rotation) that the vavle is off the seat. The leanght of duration affects where in the RPM range the power will be produced. the longer the duration( more degrees of rotation) the high the RPM will to produce torque. Lobe separation or center lineis another measurement that is very important in engine performance. This is measured in camshaft degrees. It is the distance between max. lift on the intake lobe and max lift on the exhaust lobe of the same cylinder. A higher number represents a wider separation (112-116 degrees). Cams with a wide separation have a smooth idle quality and broad power range with a flat torque curve. Peaky cams with a choppy idle and a very narrow powerband are the result of a narrow lobe separation (104-108 degrees). Lobe separation affects the amount of overlap a cam has. Overlap is the amount of time the intake and exhaust vavle of a particular cylinder are both open hen the piston is at Top Dead Center (TDC).Wide lobe separation means a shorter overlap. This creates high cylinder pressure and increased intake velocity.This high pressure is very important in low compression engines in need of good bottom-end and mid-range torque. Running a narrow lobe separation in a engine with less than 10:1 compression does not work. Cams with a narrow lobe separation need increased compression (min. 10:1, higher perferred) to boost cylinder pressure, which increases torque but only at higher RPMs. Valve lashcomes into play with mechanical and roller cams. Sometimes it is call running clearence, lash is a measurement, in thousandths of an inch or millimeter,of the distance between the top of the valveand the rocker arm. This gap is measured with a feeler gauge(engine not running),and sometimes given as both a cold and hot(after engine is warmed) setting. Hope this helps.

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1980 4X4 LUV

DAMN MAN! you answered about 5 different questions i had...thanks a lot that clears up a lot-Gus

advertised duration is usually measured different between companies, from what i've read, duration at .5" lift is one thing you need to compare cams. Just adding my 2 cents

Glad I could be some help.

Just a correction on what bob said. The duration numbers to compare are at .050" (fifty thousands of an inch). bob booboo'ed and typed .5"(half inch). Otherwise it all sounds good.
Phil

one other thing if your running a roller cam most require a bronze distributor gear. otherwise you will have metal shavings in your motor.

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don`t have the luv no more but I still like em.72 el camino,
00 & 06 silverado one 4x4, turboed vw sandrail,99 banshee, 06 raptor 700, 02 polaris trailblazer.

my bad on the typo