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914World.com _ 914World Garage _ Do CDI boxes require a coil?
Posted by: Aaron Cox Nov 5 2004, 04:42 PM
buying a mallory unilite distributor, and hyfire CDI box. does this require a new coil? no coil? blue coil?
also- my webers have vaccuum ports on them. should i go with vac advance or not on the mllory
Posted by: SLITS Nov 5 2004, 06:29 PM
And you're an aspiring engineer?
Posted by: Aaron Cox Nov 5 2004, 06:38 PM
not electrical....
now ron, in all youre mighty knowledge of porsches......
tell me por favor
Posted by: SLITS Nov 5 2004, 07:03 PM
The mallory is only a trigger device to send pulses to the CDI box. The CDI is a large capacitor(s) to feed the coil. Instead of feeding 9-12V to build the charge in the coil before collapse and using a condensor(small capacitor) to provide a short high voltage shot to the coil to slow collapse, the CDI sends a short high voltage shot and generates greater spark energy out of the coil.
Now this is all bullshit - what it in effect allows you to do is widen the spark plug gap to increase the spark area available to ignite the gas/air mixture better = bigger flame, faster start.
Answers are:
1.) Not necessarily - a blue coil is nice, a nasty coil is only as good as the remaining parts.
2. For fuel economy, yes use the vac advance unit.
Slits - Not an engineer - just old
Posted by: Aaron Cox Nov 5 2004, 07:08 PM
Now this is all bullshit - what it in effect allows you to do is widen the spark plug gap to increase the spark area available to ignite the gas/air mixture better = bigger flame, faster start.
Answers are:
1.) Not necessarily - a blue coil is nice, a nasty coil is only as good as the remaining parts.
2. For fuel economy, yes use the vac advance unit.
Slits - Not an engineer - just old
thanx ron. i knew you could do it
Posted by: swood Nov 5 2004, 10:25 PM
I got a new blue bosche coil for my setup. Yes, it too is still in the box. (LOOSOR!!) 
Posted by: MXMARK Nov 5 2004, 11:17 PM
Aaron, get the vacuum. Mine works great. Get an extra cdi for me while your at it. Thanks Mark
Posted by: SLITS Nov 6 2004, 01:20 AM
One thing I forgot to add was that generally to feed a coil, you drop the voltage to 9V with a ballast resistor. If you don't, you'll get a REALLY hot spark that will take out the contacts in the dizzy cap quickly (read eventual missfire).
The Bosch "Blue" has a built in resistor. If you change to another "hot" coil, read the instructions carefully for it's use.
Over and out!
Posted by: J P Stein Nov 6 2004, 02:57 AM
I dunno what a hyfire is but......
At risk of repeating meself, I use an MSD unit and one of their hot coils....the high vibration unit that one can mount in any position. .....no resistor. I do carry an extra rotor around as this set-up has been known to let the magic smoke out of rotors tho I haven't had the problem...yet.
A Blue coil won't supply the high voltage throughout the rpm
range to fire a plug gapped to .045.....that gap is the reason for all this biddness. 8.5mm Magnecore wires (or their equivilent) are good for keeping this voltage going to the right place.
This stuff really works. Fouled plugs are a thing of the past.
Posted by: Mueller Nov 6 2004, 10:30 AM
not electrical....
now ron, in all youre mighty knowledge of porsches......
tell me por favor
Do not use that as an excuse!!!!! J
Electrical or mechanical, does not matter, research and more research on the subject is critical, just looking for a simple yes or no answer is not acceptable, nor will you learn anything from it...
also, do not focus on only "mechanical", there will be many times that knowing basics of electrical will be very, very helpful or downright necessary…it’ll help put you at the top of your class/field……..
Posted by: Aaron Cox Nov 6 2004, 10:33 AM
whoa buddy..... im a freshman in college. onlt taking a few engineering courses at the moment. and it gets worse - Im a CIVIL engineering major
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