We had just replaced a head on a 6.0 Ford at the shop where I was working. The tech was ready to fire it up for the first time. We were standing around the truck, I was leaning on the fender, tech was on a stool at the front. Fellow in the cab fired it up and I started tapping my wedding ring on the fender. The tech yelled to shut it off and commenced to furiously check things on the engine. He said to fire it up again and I started tapping. This time he left it running and moved over by me to listen and caught me. He chased me all around the shop....