AM radio static

There is a number of ways static and noise can make it's way to any radio, AM, FM or CB/ ham, other communications

Bypass capacitors (radio noise condensers) are one. There should be a few. One is inside the alternator, another on coil +, another across the OEM instrument regulator/ limiter. There is normally one inside the radio hooked to the switched power in. If there is any doubt, you can "piggyback" one onto the rear / side of the radio, and splice into the red wire.

If your hood is not well grounded, ignition noise can radiate out through the cracks. There are various grounding schemes for the hood, including short loops of ground braid from the firewall to the hood, 1 on each side, allowing enough slack for hood open/ close.

Plug wires. Solid core / non suppressed plug wires WILL cause ignition noise. So can some ignition problems, AND THAT LONG WANDERING tach wire you through in through the firewall!!!!

Ever looked at most any Corvette? Know why they have that fancy metal junk covering the plug wires? Radio shielding........the car is plastic..............

And I don't know if it was mentioned^^ but a bad antenna/ antenna cable can cause problems