Well, I have to admit that I'm really surprised that the car was kept running, even subsequently started, after the noise began.

Kinda reminds me of my old man -- oil pressure light comes on and the engine stalls out, so he tries to start it again (got to get to work!), it runs for a minute and then it siezes. Killed a ~ 56k mile car that way.

I like Don's ideas, as always. Ticking on an M30 can mean any of an array of sounds and sources. Once you've pulled the valve cover and confirmed that the valvetrain is visually okay, you're probably alright to start the car and put a stethosocope to it.

When the valve adjustment was performed, how was the engine rotated? If it was done manually, was it turned clockwise facing the front of the motor? I've seen this a few times recently -- the hydraulic chain tensioner will fail, sometimes doing whacky things to the plastic guides and resulting in a ticking noise.

best, whit