[JMB36TA]

I posted this in the electrical section and haven't been getting any responses so I hope someone here can help.

Here's my issue. I bought a cheap Bosch tack to use to tune my fresh rebuilt 400 for my 69 bird. I needed something to set the timing and idle and didn't plan on installing it permanently in the car. I temporarily installed it during the break in to keep an eye on things but the wire from the distributor is interfering with my radio. With the tach hooked up and the car running the radio buttons sometimes don't work, it won't turn off with the power button and sometimes when I turn the car off, the volume knob don't work, the presets get screwed, and sometimes the speakers don't work. I unplug the wire from the distributor and the radio goes back to normal. I plug it in and it goes haywire again. The problem only happens with the car running, it's fine with the ignition in the on position and the car not running. I talked to the radio manufacturer and they suggested putting noise suppressing magnets on the distributor wire (I forget what they're called) so I got some and put 4 on. It helped but there were still issues with the radio. Then they suggested rerouting the wire so I tested it by running it through the driver side window but that didn't help either. It was originally routed through the firewall and behind the radio. I disconnected the tach and now my speakers turn off for a split second and makes the radio sound like a record skipping. I think it's permanently damaged. Retrosound is sending me a new radio body under warranty but I want to keep a tach in the car. I'm looking at a Stewart Warner tach to match my other gauges but don't know if I want to spend the $125 and possibly ruin another radio. I know this has to work somehow, anybody else ever have this issue in their car?