Help! These broken bits found in engine

[belfry]

I was about to adjust the valve clearances on my 1978 3.0SC engine. There was a slight ticking on the LHS.

When I removed the lower cam cover on the RHS I found these parts in the exhaust sections. I have recently had a new stainless steel exhaust fitted btw, and the heat exchangers are loose on this side. Connected to this issue?

I have been using the car loads recently and I it has been running nicely.

Who can tell me what these parts are? What do they do? Why haven't they effected the running of the engine?

I'm in a real panic. Also, annoyingly, my wife asked me if I knew what I was doing when I started doing the valves!

[belfry]

"Snapped head studs".

On the exhaust manifold?

Does this mean that I can still drive the car? The exhaust is working fine and the engine is running fine.

[belfry]

Wouldn't they have "lunched" the engine on the way through?

I've completed adjusting the valves and they're all undamaged.

[belfry]

Thank you everyone for your help

It's all coming back to me now. Almost 2 years ago (approx 2,000 miles) I read that you could use the engine as a lift point to jack up the rear of a 911. Well I tried, and the rear of the car did indeed lift. However, I thought that I must have created a manifold leak in the process as there was what sounded like an occasional exhaust blow under load. I'm now guessing that this is the noise of gas escaping from the head due to the broken studs.