what is the diff between ignition and coils
 

I'm a little bit confused about the MSD ignition unit and coil. What does each of those do? Do I need both? And how much of a performance gain would I get out of it?

Thanks
John:confused:

you need both

the coil's impedance is matched to the 'box'

the box is a transistorized ignition unit; the coil stores energy until 'told' to release it all at once

there is no big perf. gain

you need to find a 'how it works' type book or internet site and read thru that to get some background info

What if the impedances don't match? (i.e. different manufacturers)

The ignition box creates higher than source voltage (12v) via transistors and other elec. circuitry. The high voltage circuit connects to the coil primary windings. The voltage could be several hundred volts.

There are two windings in a coil (a step up transformer) - primary winding and secondary winding. Current flow through primary winding creates a magnetic field around the secondary windings. When the voltage/current signal stops (points open or other elec. signal), the mag. field stops (collapses) which in turn induces a higher voltage in the secondary winding, the end of which ends at the center tower terminal, then to the dist. cap. via the coil wire.

Sherwood

very nice sherwood
the MSD unit puts out about 450V. the coil is about 100:1 setup. that equals 45,000 V ! can you say OUCH! but it has very, very low current.
the "box" stores energy in a large capacitor.
i currently have an MSD with a permatune coil.

I found when I put the MSD 6AL and the MSD Blaster Coil on my car, it helped the low RPM and idle smoother with the multiple spark. The only thing you get on the high end is a little hotter spark. If you are looking to use an MSD ignition, I would suggest you use one of their coils as well. I'm also using a Pertronix Ignitor. My ignition has been bullet proof since making these changes. They will work just as well on a street, occasional track, to full on race car.