Electronic Ignition, WHAT TO USE Options

[BarberDave]

(IMG:style_emoticons/default/smilie_pokal.gif)
o.k., I have a newly rebuilt dizzy for my F,I, conversion. the only trouble is it still has points. I have Petroix (sp) in the one i have on my 914 with a carb now. QUES. is which electronic ignition to buy ?What is your experience?
Dave (IMG:style_emoticons/default/smilie_flagge6.gif)

[ArtechnikA]

....how does the CD improve the spark quality, does it just give an amplified pulse to the coil?
Also how does it preserve the points ( I.E. no pitting )

last point first. with a conventional Kettering ignition, -all- the spark energy is being switched by the points. a CD is only triggered by the points - the actual spark energy is generated in the CD unit with its own direct power connection. it is exactly like using a relay in a headlight circuit to isolate the switch from the full current of the lamp - except that it is much, much faster ...

so - there are several benefits to the CD's spark. since it can draw as much current as is needs without affecting points life, it can deliver much, much more energy to the spark. the coil in a Kettering ignition is an energy reservoir - it is charged with electricity when the points are closed, and when they open, the magnetic field created inside the coil collapses and an electrical pulse is created in the secondary side which fires the plugs. but it takes a relatively long time to charge a coil to full capacity, which is why 'dwell' (the amount of time, really, the points are closed) is so important.

capacitors are much more efficient energy storage devices, and they charge much, much faster, in part because they operate on voltages much higher than the 12V available to the Kettering coil, using a DC-DC power convertor found inside the unit (that's where the whine/whistle comes from).

they can also discharge their stored current much faster, so you have a precisely timed, high-energy spark with a very short rise-time that's excellent for firing a spark plug under harsh conditions.

that's the basic CD ignition - lots of energy from a direct power connection, places very little load on the trigger points, fast spark impulse.

as the systems improved over time, the "coil" had to change, because it changed its role from an energy-storage device to a true pulse transformer.

at this point, you can start adding doo-dads - if a CD ignition can recover so fast between sparks, maybe if one spark is good, more is better? enter the multiple-spark discharge type devices. since we now have electronics controlling the spark, we can measure the time between pulses and shut down the spark when the engine's running faster than desired - a rev-limiter function.

when you start sending huge amounts of energy into the spark plugs, you have to make sure all the high-tension stuff is up to snuff. (i had a non-Bosch dizzy rotor -explode- after just a few weeks' service with the MSD...) good cap and rotor, preferably Bosch, and good ignition wires. i like Magnecor because they work, the price is right, and (a sticky issue for 6-cyl cars...) the 911-style plug connectors actually fit.