I believe these cam advance your ignition
Cams have nothing to do with ignition
basically, an engine is a pump - the more air you can get in (and out), the more efficient it will be (or the more power it will give)
Think of it this way - a standard Coupe will produce about 220bhp at its peak - ie its working absolutely flat out.
My Coupe will produce 220bhp at about 2/3 throttle and at far less revs than standard, so its using less effort (and thus, less fuel) to produce the power.
The way to achieve these gains is to make the 'pump' more efficient - to do this, we remove as many restrictions as is possible. One of the biggest restrictions is the cylinder head, and particularly, the valves.
Valves are measured in three ways - lift, duration and timing. Lift is how far they open and duration is (predictably) how long they are open for and timing is when they open (and close)
the standard cam timing is designed to produce adequate power with decent torque and OK(ish) fuel consumption.
Changing any (or all) of the cam's attributes can change the way an engine behaves. It might produce more power. It might produce less power, but with more torque. It might increase the revs needed to produce the power, or it might extend the rev range over which it makes the desired power.
Note that cam timing is critical, but it also has funny effects, dependent on revs. At low engine speeds, timing of the valve needs to be very different to high engine speeds. This is all to do with the speed of the inlet charge entering the cylinder. At low speeds, there is no problem filling the cylinder, but at higher engine speeds, the pistons are moving much more quickly, meaning there's far less time (like 1/200 of a second at 6,000rpm) to open the inlet valve, get the fuel/air mixture into the cylinder and get the valve close again. This is why many modern engines use camshaft variators to alter the timing of the inlet cam (and sometimes, but rarely, the exhaust cam) to provide different characteristics at different revs.
For a truly innovative design, look at the new Fiat MultiAir engine, which doesn't use an inlet cam at all - it now uses pnuematically-controlled valves to deliver the air to the cylinder (and at some revs, the valve opens and closes more than once per cycle - very clever)
There - Sunday AM tech lesson