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Can anyone help with the capacitors on my 53 Cavalier that are used for noise filtering? I have the following 3 capacitors that are rated the same, .5 MF, but all have different part numbers, which are of course obsolete part numbers. It may be the different part numbers have more to do with the bracket and lead style than the actual capacitor, but I'm having trouble figuring that out.


The capacitor on the generator is a 1925118 (.5 MF)
The capacitor on the coil is a 1917580 (.5 MF)
The capacitor under the dash connected to the ignition switch is a 7259643 (.5 MF)
The capacitor in my Delco Remy distributor has no part number on it, but the correct modern part number should be an ECHLIN RR-134

Any thoughts you have would be appreciated!

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The capacitors on the generator and ign switch are for filtering. The one in the distributor is not. That one is part of the point and coil circuit. Radio noise suppression on distributors was done via an inline piece which I think might be a resistor inserted in the high voltage lead coming from the coil.

Not sure if you are looking for new capacitors or just information but if looking, even if you find some old NOS items with the correct part numbers, being the old style wax and paper construction there is every chance they would be in poor shape. Also, depending on who installed the radio -- factory, dealer or aftermarket vendor -- the part number and style of capacitor could be different.

Napa carries an assortment of freshly made radio suppression capacitors, some of which resemble the old items.

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NAPA carries the capacitor for the 55-56 generator, may also be appropriate for earlier years. Catalog number is RC 1.

Sounds like capacitoritis back in the day. Cheap - use lots of them.
This was a relatively new invention for autos and widely applied. The one inside the dist is for the wave form for the spark so it doesn't jump around the contacts and cause damage/burnt points.
If think the generator one is for overvoltage/spike protection, not radio per se. 0.5 mF (milliFarad) is the capacitance rating - common size. How much energy it'll take.
I was under the impression most of this static suppression was due to using solid spark wires. Not so much a problem with graphite core wires. I know the C1&2 Corvettes were particularly vulnerable with the AM due to no steel body to suppress things. They had a stainless shield behind the dist.
I guess with tube radios, it's harder to filter out the static also.
I've even seen thing in hubcaps supposed for this but never seen any proof of need.

I used to have issues with radio static in very dry weather caused by static discharge through the front wheel bearings. The tires rolling on pavement caused the static charge buildup.

The weather and the road surface would affect the noise. In some cases, patched sections of the roadway would not cause the static, while the unpatched sections would.
The cure was to put a device in the front hub caps that made good electrical contact between the wheel assembly and the chassis. This usually was a spiral bronze spring with a contact button that fit into the center drill hole in the front spindle.

I haven't had that problem in years, and I have not seen one of the devices on any newer vehicle. It may be that tires with steel belts do not need them, or that modern wheel bearing lubricants are non-dielectric. (?)


A generator without a filter capacitor can cause radio static, as can most any brush type motor or generator.

Alternators can produce a whine, and fuel injection systems can generate AM interference.

Poorly-grounded antennas and body panels cause a lot of AM radio interference.