A few months ago, I removed my old Chevrolet Inline 6 cylinder motor, and installed a Chevy 350 V8 into my 1963 Chevrolet C10. Immediately after installing the 350, I noticed my aftermarket JVC head unit would not work properly. When ever the motor was running, the sound would cut in and out, making the stereo virtually impossible to listen to. Some people describe this noise as a ‘popping’ noise, but my experience was that the sound was just going in and out.
After hours of research, most people said to check my grounds for the stereo, battery, and motor. I cleaned up all my grounds, and the problem still persisted. Further research hinted that I might be getting interference from the HEI distributor. RadioShack sells Ferrite Core Filters, that snap over the power wires which are affected by the EMF. Honestly, I don’t fully understand how they work, but they some how clean up the EMF interference in electrical current. I went to RadioShack, and found part number 273-0067 which contains 2 Ferrite Filters. I purchased two of them (for a total of four filters). I installed 2 filters on each power wire on the stereo. When you do this make sure you install the filters as close to the stereo connector as possible. There should be one power wire which is constantly hot (usually red), and a second power wire which is only hot when key is turned to the accessory position or the engine is running (on my JVC this wire was Yellow). Installing these filters helped a little, though it didn’t completely solve the problem. It did however confirm that the problem was probably coming from EMF interference from the distributor.
Discovering this, I decided to trace my distributor wiring, and discovered both the Tach and Power wire ran from the HEI Distributor, through the firewall and under the dash …. RIGHT ABOVE THE STEREO. I knew I was on to something. I disconnected the wire to the tach from the distributor, and the problem virtually went away. The Tach wire was causing some kind of interference. I also suspected the power wire my be contributing to the problem as well.
Due to lack of time and motiviation, instead of rerouting the wires away from the stereo, I decided to come up with a temporary solution and wrap the wires in aluminum foil to see if it would shield the EMF coming from the HEI Tach and Power wires and clean up the sound on the stereo. After wrapping the wires in foil, and then wrapping that up with electrical tape to hold it all together, combined with the Ferrite Filters the choppy sound from the stereo was about 99% gone.
The correct way to fix this would be to re-route the wiring so it does not come near the stereo, and continue to use the Ferrite Filters on the stereo power wires, but for the time being this solution is working. I hope this helps anyone else who is experiencing this problem. Searching on Google results in tons of these reported problems, but few answers.
Here are a few pictures to detail what I did: