Radio Interference with Points Ignition

Old August 14th, 2012, 07:53 AM
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Radio Interference with Points Ignition

Taking a stab in the dark as to which Forum to post this in, but "Electrical" makes the most sense I guess..

My daily driver ('55 Super 88) is a bone-stock setup, including the ignition system (i.e. 'points').

There is an aftermarket radio in the glove box that was there when I bought the car, and there is a lot of 'noise' from it (AM or FM) - I say "noise" because it's more noise than static, but it's annoying nonetheless.

The capacitor on the coil is typically for radio interference I believe - outside of changing this out, any suggestions to reduce noise in the radio? - I'm fairly certain that the source it the ignition system since it goes away when the car is off / radio on.

Thanks
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Old August 14th, 2012, 07:59 AM
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Change the cap on the coil, make sure your antenna and radio chasis ground is clean and secure. Also leaking spark plug wires or non resistance wires will cause it.
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Old August 14th, 2012, 08:11 AM
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Is the radio hooked directly to the alternator for power? (The 12v terminal on the back) If so move it to the fuse panel. Radio Shack also makes noise filters that will eliminate this.
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Old August 14th, 2012, 09:28 AM
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For a quick test run a hot wire from the radio directly to the + side of the battery and see if it still crackles and pops, if not start looking for bad ignition wires,distributor cap leaks, bad ground ect.....Tedd
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Old August 14th, 2012, 04:24 PM
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i'm not certain about your vintage of Oldsmobile, but the cutlass distributors had radio frequency interferance shields surounding the points. if your distibutor came with these, but have gone missing ,that might be something to consider. they do help because i tried running the car without them installed and the radio was impossible to listen to, a constant buzz as the points opened and closed. just another suggestion, hope this helps.
cheers,
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Old August 14th, 2012, 04:36 PM
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Originally Posted by TripDeuces
Is the radio hooked directly to the alternator for power? (The 12v terminal on the back) If so move it to the fuse panel. Radio Shack also makes noise filters that will eliminate this.
X2...usually you mount the filter by the regulator on the firewall. It helps quite a bit.
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Old August 14th, 2012, 06:31 PM
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Originally Posted by Olds Dad
....The capacitor on the coil is typically for radio interference I believe - outside of changing this out, any suggestions to reduce noise in the radio? - I'm fairly certain that the source it the ignition system since it goes away when the car is off / radio on.

Thanks
Without me taking a hike out to the garage to look, isn't there a capacitor on the generator also?


Originally Posted by john paul
i'm not certain about your vintage of Oldsmobile, but the cutlass distributors had radio frequency interferance shields surounding the points. if your distibutor came with these, but have gone missing ,that might be something to consider. they do help because i tried running the car without them installed and the radio was impossible to listen to, a constant buzz as the points opened and closed. just another suggestion, hope this helps.
cheers,
John Paul
I remember those. Often they got trashed as a pain in the backside because they are a pain without some kind of screw starter tool. They did not exist in the 50's and so there isn't any tapped holes in the plate to mount them if you could find a set. But it's an interesting idea for a modification. Thanks!
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Old August 14th, 2012, 08:18 PM
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Originally Posted by TripDeuces
Radio Shack also makes noise filters that will eliminate this.
Do they? I couldn't find anything on their website. The Radio Shack of a generation ago would have had it, but the Radio Shack out there now is not your father's Radio Shack. They've become an abridged, miniature version of Best Buy.


Crutchfield, however, shows a radio noise filter for $12.99.

http://www.crutchfield.com/p_003S15A...t.html?tp=2653




You could try this site, too.

http://www.hifisoundconnection.com/S...9952/SFV/30046

Last edited by jaunty75; August 14th, 2012 at 08:22 PM.
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Old August 15th, 2012, 06:44 AM
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There may also be a cap. on the voltage regulator.
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Old August 15th, 2012, 08:34 AM
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All good suggestions...I know that "electrically", condenser and capacitor is the same animal - anyone know if these are the same ones? (i.e. one on the points = one on the coil = one on the generator = one on the voltage regulator?) -

I'm going to try changing out all the ones I can find...if that doesn't help I'll try a physical noise suppressor.
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Old August 15th, 2012, 09:33 AM
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have you checked the gen or alt output for noise on the line or a/c volt output. had a pickup that had a/c volt output from alt driving radio nut when running
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Old August 15th, 2012, 01:22 PM
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Originally Posted by TripDeuces
Is the radio hooked directly to the alternator for power? (The 12v terminal on the back) If so move it to the fuse panel. Radio Shack also makes noise filters that will eliminate this.
No alternator on a 55 unless modified....Tedd

Last edited by Tedd Thompson; August 15th, 2012 at 11:41 PM.
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Old August 15th, 2012, 02:23 PM
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i was taking about a\c ripple from the doides in the alt redfeir being bad. surpressor on radio won't fix problem
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Old August 15th, 2012, 11:38 PM
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Gorden,

On the deluxe radio there is an adjustment that puts the antenna in tune with the radio if this aftermarket unit wasn't properly tuned when installed this could be the problem, the adjustment is located( on an original radio) next to the antenna socket and a small screwdriver is used to adjust it. Put the radio on a weak signal then turn the screw back and forth till the station is at its strongest. This should do it if that was the problem....Tedd
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