Engine interference in Radio
Thread Starter
Melting Slicks
Joined: Sep 2006
Posts: 2,814
Likes: 469
From: Wichita Kansas
Engine interference in Radio
I recently reconnected a refurbished stock stereo in my '72 and am getting an all-to-familiar interference noise; it is so familiar, however the fix is not recallable. I have 4 speakers, each 4 olm, hooked up each set in series, two in kickplates, two in back. The distributor is not what came stock in this 350, it has electronic ignition now. Am I going to have to install plug shields? Thanks, I did a search and did not find any solutions.......................
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
If the "noise" frequency changes with engine RPM, then your problem is ignition interference. The best way to deal with that is:
#1 - Make sure the radio have a very good ground connection (if not sure, run a dedicated wire directly to a battery ground line).
#2 - Install either shielded and grounded ignition wiring (like the big blocks used) OR the original plugs, wiring, and distributor shielding.
#3 - Make sure the filter capacitor for the alternator is installed and operational. You might still get some "pops" when you use the brakes or turn on wipers, etc. if you don't have filter capacitors installed where they are supposed to be (refer to A.I.M. for locations).
#1 - Make sure the radio have a very good ground connection (if not sure, run a dedicated wire directly to a battery ground line).
#2 - Install either shielded and grounded ignition wiring (like the big blocks used) OR the original plugs, wiring, and distributor shielding.
#3 - Make sure the filter capacitor for the alternator is installed and operational. You might still get some "pops" when you use the brakes or turn on wipers, etc. if you don't have filter capacitors installed where they are supposed to be (refer to A.I.M. for locations).
Le Mans Master
Joined: Jan 2007
Posts: 7,992
Likes: 3,334
From: Omaha NE
2025 c3 ('74-'82) of the Year Finalist - Unmodified
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When I hit around 40K I started getting RPM type interference for the first time. I put on a new set of AC/Delco plug wires and that was that.....
