I just put a new Sony radio in my 84 Spider. The only issue is extreme static(just in AM reception). The static follows the engine revs.
My solutions? I disconnected the windshild antenna and installed a rear post antenna. With noise filter. I also installed an aftermarket in-line power supply filter. (I question the need for these)
Also replaced the plug/coil wires with new Bosch from IAP.
Seems to have improved, but is still very loud. What have I missed? I suspect perhaps something in the charging system?
a ground for the hood and exhaust help a lot, the exhaust hangs by rubber hangers and acts like an antenna. a ground strap across the hood hinges helps keep the noise inside. alternator noise is usually a whine that gets higher pitched with engine rpm, spark plug noise is a popping that gets faster with rpm. the fuel pumps also can get noisey, thats where I would put an inline filter.