So here's the deal, my partner isn't a car guy so unfortunately I hear about things that need to get addressed a bit late. Two weeks ago I noticed the brakes were grinding, discovered he had chewed through the pads and was wearing the rotor surface. Replaced all the pads and rotors, flushed the brake fluid. Then I noticed that the valve cover gasket was having an issue and was leaking oil so I went and got new gaskets, pulled off the valve covers, replaced them both and torqued them down. Idled the car at various angles to be sure the leak was fixed and being pleased with myself I took then revved the engine only to hear a really disturbing sound from the front of the engine. Since all my tools are accounted for I'm sure I didn't drop anything in the engine. I was hoping it might be a harmonic balancer but since only the secondary chain and tensioners have been replaced (~135,000 miles) I'm thinking it may be the primary tensioners that have failed and are allowing the chain to slap? I have attached a zip file that contains the sound clip of the engine revving to around 3,400 RPM. I made sure the car hasn't been used since and am hoping to tow it to my local Jag indy tomorrow. Anyone know what this could be? What is likely?