Yellow truck: 79 F350 460 C6 4x2 Duraspark II blue grommet

other day I ordered a "radio ignition interference filter" for the coil. (Thanks, Bill, for the partnumber and sources)

what exactly is this? It looks like a condenser for a points style distributor. Are these similar or compatible?

anybody know the specs on the device? Microfarads? Maybe a guy could get a generic at radio shack or Frys?

are these generally the same across manufacturers/ignition types?

and finally, will the wrong one cause damage?

 

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They might work OK for ignition points in a pinch (if it would fit/or run a wire and mount it outside distributor) the capacitance is quite a bit higher if I remember right so the points would probably hork out fairly quickly, Mustangs Forever or somebody like that sells the radio interference reproductions. An ignition capacitor is probably too small to be effective for radio interference work, but it might help.

They were kinda pricey for what they are so I didn't buy a repro one. The manual may have the capacitance spec. If they short out (to ground) the engine wouldn't run I expect, but otherwise can't hurt anything.

They used to stick 'em all over - on generator armatures, alternators, voltage regulators, as well as the coil. You'd also see in the same vein the coil to distributor cap lead tied in a knot, in radio work the wiring is always as short and direct as possible. If the coil wire is "too long" it can cause radio interference. In this instance, they were trying to prevent the engine and ignition from becoming a "transmitter" of EMI.

These old trucks equipped with Solid core spark plug wires, non-resistor plugs, generators and mechanical voltage regulators etc, would wipe out Radio and Television reception when they'd drive down the block.

Ignition condensors are closely sized or matched to the coil as they are part of a resonant circuit or somesuch, usually right at 0.22 MFD (microfarads) or uF or whatever the hell they call it now. It's a lot of capacitance in a fairly small package that has to withstand a couple hundred volts hundreds of times a second. Prevents arcing of the points and makes the spark at the plugs a lot hotter than it would be otherwise. When points were used a mechanic could tell by looking at the points if the condenser was the right size, capacitance wise. Due to production variances one side or the other of the points would have more material, wearing unevenly. By lengthening or shortening the condenser wire itself he could change the capacitance slightly, just enough so the points would wear more evenly. If the points were wearing well, the rule was usually just leave it alone.

Today nobody hardly can make an ignition style condensor worth a damn. A modern 600 volt poly film cap of the same capacity is only a couple bucks and would work to kill EMI at the coil or elsewhere (or work as an ignition condensor for that matter) Radio Shack doesn't sell those values of capacitors anymore but Mouser and Digikey do. It wouldn't look concours but it would do the job.

Have been meaning to install a couple on my gennie and regulator equipped '64, it sounds like a chainsaw over radios and CBs and things like that.

 

I'm curious as well. I just pulled one off of the back of an alternator this last Monday. It was and seems to have been inoperable for some time judging from the rpm base whine in the aftermarket OEM style radio in a '65 mustang.
Long story short, I had to replace the alternator with the old one with burnt and separated wires. The old one had was turned out to be a radio interference filter. Being in an on-road breakdown I did not look into hooking it back up/replacing it. Since owning this car there has been radio interference, so at a minimum our device was not working. I didn't know it existed. What is this magic, and where is the best spot in the electrical system to place it?

 

Look in the Shop manual - this is outdated a bit but does show one of them newfangled alternators too, and the same principles apply.

 

On the '73 models they were mounted by the voltage regulator. Ford also mounted them on the coil.

 

Thanks, guys, for all the great info. I ordered a rather pricey but correct part number, but it has a loop connector on the end of the wire. I was thinking I might save it for a coil with the screw-on leads.

On eBay,I saw a bunch of AC delco and other condensors with spade and butt connectors for cheap. Not knowing how they worked, I didn't want to take a chance on frying the system

 

Jeeze, you need to get some mud on that thing! (kidding)

So I got to thinking (always a sketchy deal there) what side of the coil does the capacitor go on? The negative side or battery side? Capacitor/condensers can short out or, go open. A shorted cap to ground on the negative side would kill the motor afaik. Positive side not sure what would happen, blow a fuse maybe.

It might not be a bad plan to test condenser/capacitor at their rated voltage before installing them in those applications. Capacitor checkers and DMMs can't do this however.

 

thanx for info

 

F6UZ-18801-BA replaced D5AZ-18832-A

With/without DuraSpark makes no difference. DuraSpark introduced in 1974, but not all vehicles came with it until 1976.

D5AZ-18832-A replaced C6OZ-18832-A: Applications:

1966/79 most FoMoCo vehicles; 1980/82 all FoMoCo vehicles; 1983/89 Crown Vic/Grand Marquis/Mark VII/Town Car / 1984/89 Tempo/Topaz/Continental Sedan.

I didn't look after 1989.

 

My memory is a bit shaky on these but as I recall the condenser-style filters under discussion only filtered spark noise. I believe the correct filter for alternator whine was a essentially a small transformer. There was a third type of filter which went in-line on the coil wire - you cut the coil wire, then screwed it into each half of the wire. Problem was, when it failed you were stranded - so it was not used much. The manufacturers got pretty good at building the filtering into the cars, so the aftermarket installers rarely had to install filters much past the '70s.