Hopefully mods will move this to the "Under the hood" section to get you a bit more views....

 

Did you remove the accessory belt yet to see if its anything related to the tensioning pulley or other components? May not be the engine at all.

 

[left]^^^Agreed...you need to isolate the noise to the drive belt side or timing chain side. So pull the drive belt off and run the engine again. If the noise is still around you know it’s something in the timing chain area.
If it goes away obviously it’s one of the driven accessories or pulleys on the drive belt.

To me it it sounds like something with the chain isn’t jiving. And you could always pull the valve cover and check the cam timing to be sure it hasn’t jump as well, which could be a sign of a worn out tensioner or chain. Best of luck and keep us posted...I always like the weird ones that are tricky to figure out

 

Personally I think it sounds like its timing chain related. Get that Aux belt off so we can isolate it.

 

Definitely sounds timing related. As AndyPandy suggested, get the aux belt off to eliminate a few things.
Also, take the oil filler cap off - is it coming from under the cam cover?
The only sound I've heard like this was a broken rocker on a Cobra replica - obviously you don't have a broken rocker, but a broken cam follower maybe?
Worth lifting the cam cover & looking carefully...

 

Looking at this logically, lets assume your engine is idling at around 900 rpm - that's 15 revs/sec
That ticking sound at idle speed seems to me to be coming at 7-8 ticks/sec or half crankshaft speed.
That's one tick per cam revolution, take a good look at the cams & followers.

 

Check the valve clearance. Impossible to break a follower/rocker arm, on the s2k they're roller rockers and are in contact with the cams at all times. All vibration and resonance is taken up by the lost motion assemblies.

 

Someone just posted in a current thread about chasing a engine noise and they said they found it in the lost motion assembly, with too much slop/play. No further details then this currently. Don't think i've ever heard of this before.

 

That sound is way too familiar to me. Sounds exactly like my SR20DET back in the day.... before a rod went through the block (due to oil starvation from dented oil-pan/pick-up blockage).

Sorry man.. best of luck with the rebuild or new engine swap.