1970 911t engine noise

[Andrehasaposse]

Hi guys. Had a great summer driving my t after getting it back on the road after sitting for years. Tried to get away with a top end rebuild but developed a terrible engine noise after a couple hundred miles while out driving with my wife. Pulled the engine and found the 123 side cam nut had backed off and shredded the timing gear. Leakdown test showed 2-3% across the board so Replaced the sprocket, gear, and pin. Retimed and reinstalled only for the noise to persist. I figured it had to be rod knock so pulled the engine again and pulled off the pistons and cylinders and no appreciable play in the rods. Even pulled the bearings and they “looked” good. No carnage.

What’s your thoughts on this noise. Chain tensioner? Broken valve spring?

Sorry for the ****ty video. Definitely sounds like it’s coming from the 123 side.

https://youtube.com/shorts/Q4XiKTpleCo?si=KFpDD3377umpWZ9G

[85RedCarrera]

I don't know, but you definitely need to stop running the engine and start disassembling, before you destroy something else.... fan and fan shroud?

[PeteKz]

That doesn't sound like rod knock to me. But stop running it until you find the source.

Thoughts: Make damn sure your cam timing is right, and that you have valve to piston clearance at TDC overlap. Pull heads again and make sure no valves are bent. Check exhaust gaskets are not loose or blown out.