Coil Cond.

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Dizzydean

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The condenser to the ignition coil had the wire fall out while I was attaching things. Its the original from my 67 so its lasted a while. Is this a necessary item. If so how can I replace it or am I still good.
 
It's a radio static suppressor, not necessary for your engine to run, but you may have radio static that rises and falls with the engine speed. A car stereo shop may sell them or one of the resto shops should sell them.
 
Parts stores have generic replacements. I used to know a part number or two
 
I use a 60 cent 0.33 uF 250 VDC film capacitor and add leads. The capacitor provides a lower impedance AC path to ground for the spark current. The ignition coil is an auto transformer, when the spark happens current needs a complete circuit. The path is ground, battery, ignition primary wiring, coil primary, coil secondary, plug, and ground. The capacitor shunts the primary ignition supply, including battery at the coil, providing a near path for the AC spark current, reducing it from the primary ignition supply.

Here is an expensive one with part number.
http://www.billrolikenterprises.com/proddetail.asp?prod=2884869
 
Most modern radios have their own filters on the power input. Also, FM is much less susceptible to noise. Without that cap, you may mess up other driver's AM radios, but that is mostly political-rant and sports talk stations anyway.
 
And when the capacitor is close to coil, it does the best job. A filter at or in the radio is too late for radiated EMF, it helps only with conducted noise on the power entry. The radiated EMF happens between the coil, and the wiring back to the source and ground, becomes an antenna. The radio picks up the noise via the antenna. The spark signal is rich in frequencies, so there are many frequencies that are in tune with the wiring length back to ground. The capacitor greatly shortens the length to a few inches, reducing the noise spectrum. Harmonics decay with the reciprocal of the odd harmonic number. The capacitor also results some in improved spark energy to plug, using the energy that would otherwise be radiated as EMI.
 
All true Kit, but probably doesn't matter in practice since when I took the coil off a Magnum engine, I didn't see any capacitor near the coil, and it mounts way at the front of the engine.

I used to have students in a Physics lab play with SCR's which chop the AC wave to proportion power, i.e. your common light-dimmer switch. At low power, the wave is chopped early, giving a sharp acute angle (viewed on O-scope) which gives high frequencies. We put an AM radio next to it to demonstrate "Radio Frequency Interference". In FM mode, you hear no static.

I left one out. The AM band also has preachers ranting.
 
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