Diesel Bombers - Sounds like a HUEY

YouTube- VIDEO0002.mp4
Just did injectors and adjusted the valves. Everything was fine when it came outof the shop. Took a drive and blew the IC line off the drivers side. Stopped to hook it up and the motor sounded hot, like there was a coolant leak. Fixed IC and went looking for the leak, and found nothing. Started it up and looked again and heard this noise. You can not hear it in the cab once you raise the rpms. You really have to lissen to hear it before you raise them. I am trying to identify what is causeing the noise. It is definatlyu comming from the air intake horn.