Ideas on what's causing my click/tick/rattle noise?

I read through this entire thread and didn't see anything other than it's rpm related. Is the tapping/ticking at engine speed, half engine speed, double engine speed..... You may ask how do you tell? At idle I've used a timing light on a spark plug. That is half engine speed. You mentioned that it gets louder above 2000 rpm. In neutral or driving? I am just throwing this out there but I chased an engine speed tick in a SBC once that turned out to be the fuel line from the carb just hitting the back of the harmonic balancer.