Thanks for your quick reply, Brian.

I measured the IP timing some time ago with the locking bolt and it was spot on, 15 degrees. I guess somebody adjusted the IP at some point before I got the car.

The procedure I followed to measure the valve timing is just as described in the FSM. By repeting the procedure 3 times I tried to minimise the risk of doing it wrong (i.e. gauge bad positon).

The marks on the camshaft and the head were slightly misaligned at crankshaft OT, reinforcing the idea that the chain is streched.

I will now consider replacing the chain.

Regards
gonzalo