Little help someone?, Mechanical question Options

[Wishful3S-GTE]

My knowledge on mechanics is very limited but I'm not completely in the dark. I was just wondering what the measurements of the cam gears represent. Like 256 for example and why tuners use diff sizes or angles or whatever it represents for each cam.

[SpedToe169]

There are a number of different parameters that define a cam. Just a few of them are: Lift, duration, duration at 0.050, IVO angle, IVC angle, EVO angle, EVC angle, overlap, and a few others.

Lift is just the total lift of the cam lobe, i.e. the difference between the base circle radius of the cam and the radius of the point of max lift. Duration is how long (in degrees that the valve is open. It can also be defined as the number of degrees where the lobe radius is greater than the base circle radius. Duration at 0.050 is just used to get an idea of how steep the ramp on the lobe is. The four different angles are Intake Valve Opening and Closing angles, and Exhaust Opening and Closing angles. Overlap refers to the number of degrees that the exhaust valve remains open after the intake valve has begun to open.

Different values of these parameters will produce vastly differently behaving engines as well as producing different power and torque numbers at different rpm. There are a lot of things that will determine what cam will work best for what application. I really don't have time to go in to it all, there have been many books written on the subject, its that complex.

Also check out:

http://auto.howstuffworks.com/camshaft.htm

for answers to some other questions you'll probably have. If you have more specific questions, let me know and I'll try to help you out.