Holley Retrobright radio interference solutions?

So I bit the bullet and put the LED headlights in- and they are great! BUT they also totally kill the FM radio. Tried just sticking these ferrite cores (https://www.amazon.com/dp/B08DC9JF5K/) on the leads, but no joy. Called Morrimoto who makes Retrobrights for Holley and they said I need to loop the wires through the core- I wasn't clear on how they would do that with a 1/4 inch ID snap-on core, so will call back. Wondered if anyone has anypics of a proven solution that they've used or if anyone tried using the larger doughnuts like one might do for ham radio- like wrapping the leads around these 55 mm doughnuts https://www.amazon.com/dp/B07PDMWN57/ since the plugs will pass.

Make sure he hood has a ground strap to the firewall. This makes a big difference for FM in the fringe areas.

Believe it or not, the radiator support can also loose it's ground from rusty bolts/surface on the mounting bolts to the fenders. All the front sheet metal needs a ground, easy to test to make sure all the pieces have a ground.

Turbo4whl said:

Make sure he hood has a ground strap to the firewall. This makes a big difference for FM in the fringe areas.

Believe it or not, the radiator support can also loose it's ground from rusty bolts/surface on the mounting bolts to the fenders. All the front sheet metal needs a ground, easy to test to make sure all the pieces have a ground.

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It's interesting that you mention the hood. Here's my related issue that you may have some insight on:

Years ago, I replaced the sealed beams with LED headlights on my Chevy Celebrity. They killed the FM reception, even on good, strong local channels. It's a unibody car with a steel hood, but the headlights are mounted in the fiberglass header panel. I installed those ferrite things on the leads (not looped) and it did help, but reception still isn't the best.

Now at work, we've installed the very same type of LED headlights on numerous GM medium duty trucks and the headlights have never hurt the FM reception at all. Those headlights are mounted in the front of the fiberglass hood.

What is causing the results to be so different?

@Turbo4whl , don't have a ground strap on the hood but ohm meter between hood and firewall shows good connectivity- same with radiator support. @bucket , When I talked to the Morimoto guy he said the loop was the only way to get rid of it. Oddly, my prior LEDs had no RFI

@saltdog The only reason GM has a ground strap on th hood is for the radio. The hindges can loose their ground driving because the hood shakes. I only guessed it might be an issue. If the LEDs are putting out interfearce they must be the problem

Side note, I put Auxbeam LEDs in my '06 Chevy truck. No radio issues from them. Q20 series I believe, they even have a small cooling fan. These lights recommended by a fellow mechanic. No more shadows of my truck in front of me when being tailed by a new vehicle with bright lights.

Interesting. I didn't lose any FM ability with my RMS LEDs in my '85 but in all 8 of my NBS trucks, as soon as I install LED or HID lights, the radio reception goes to hell. Haven't tried anything to fix it, I just live with it and mostly stream music anyway

saltdog said:

So I bit the bullet and put the LED headlights in- and they are great! BUT they also totally kill the FM radio. Tried just sticking these ferrite cores (https://www.amazon.com/dp/B08DC9JF5K/) on the leads, but no joy. Called Morrimoto who makes Retrobrights for Holley and they said I need to loop the wires through the core- I wasn't clear on how they would do that with a 1/4 inch ID snap-on core, so will call back. Wondered if anyone has anypics of a proven solution that they've used or if anyone tried using the larger doughnuts like one might do for ham radio- like wrapping the leads around these 55 mm doughnuts https://www.amazon.com/dp/B07PDMWN57/ since the plugs will pass.

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snap on ferrites are about 1/10 as effective as a single torroid with 10 'turns' through it.
to further complicate, the 'mix' of the ferrite determines the frequency range it is most effective at.
you'll want a mix 31 or 43 for common mode suppression up to 300mHz.

on the power AND the antenna coax.

as others have mentioned, some 'makers' suppress the rfi better than others.
basically, if everyone driving used only broadcast radio, the makers would feel pressure to not interfere.

i run amateur radio in the hemi ram and rfi is a pain in the butt to get rid of.

good luck
'monkey
KB0WLF