How do I decode this cam stuff? Overlap, degree duration what does it all mean?? Help me!

It all depends on your combination, basically what do you want to do with the motor. Things such as automatic or stick, compression ratio, rear end gearing, weight of vehicle, idle quality desired, cubic inch, intake to be used, heads to be used etc. heres a basic over view
-Actual Duration is the length in degrees that a camshaft has the valve open, the more you have the higher up your RPM range will be and the rougher the idle, less vacum. Actual duration is effected by how aggressive the ramps are where one cam could have 245 dur. @.050 lift and an actual of 300 degrees, where as another cam with 245 @ .050 lift could have an actual duration of 290 degrees. the cam with 290 degrees actual duration would have "more aggressive ramps as theres less difference between the actual duration and the .050 duration. This is where things can get controversial but it is true that the more aggressive your ramps the more power you will make. This is why the Comp XE series of cam is popular right now but there are DEFINATE downsides to having a very aggressively ramped cam. But that could be covered later if your curious
-Duration @.050 lift is a more accurate way of detirmining a cams RPM range, idle quality, again the more you have the higher your RPM range will be and the rougher the idle.
-Lift is not how long the valve is open but a measure of how far the valve travels off the valve seat. More lift is good but you have to have the correct valve springs and have your heads set up properly and there is a certian point where too much lift is a bad thing for reliability. More lift = more valve spring repairs and replacement and is harder on your valvetrain.
-Lobe seperation is exactly that the degrees in seperation between the "peak" ofthe intake and the "peak" of the exaust lobe. More seperation {110,112,114} is good for a broader power band, better idle quality, more vacum and is required for the use of power adders suchas Nitrous, Superchargers. A wider L/S is good for a street automatic car. A narrower L/S gives a power band more peak power, rougher idle, less vacum and is more common among race cars or stickshift cars. these cams are harder to get idleing. Theres more to it but thats all i can think if right now. Hopefully harold will chime in and correct me if im off on some of it. Good luck, If you list your combo we could be more specific on why a cam would work rather than just giving such a broad explanation.

Get a Summit cat. and check out what they list as cam usage ranges b/c it is fairly straight forward.

It basically says small cams run at low rpm's and are pretty much streetable whereas big cam's run at high rpm's and are generally moreso in the "race" category.

But again one guy's big hairy cam in a small engine is just another guy's daily driver cam in a big engine so a lot of things come into play with respect to cam choice.

You will do very good here by just asking for everybody's advice on this b/c there have been a lot of different engine combinations ran, thus a wealth of practical experience..

pdq67