Hi guys

My headgasket went on my cosworth last week so over the weekend I changed the gasket.

Anyway I started the car up and it sounded fine and ran smooth straight away, let it idle fo a min or two and noticed the pulley making a bit of a noise. So stopped the engine and the cambelt was a little tight. As I undid the tensioner the belt slipped off one of the top pulleys, so I realigned it thinking I had it just as before started it up and now getting a rattle from the top of the engine near number four cylinder on the inlet side. Its very loud and I defo wouldn't want to drive it or let it idle for any period of time. I have checked and double check the timing and I know its spot on. The car runs on all four cylinders and idles ok. I think I might of bent 1 valve as its definitely running on 4!?

Any idea?

Thank you

(On another note iv never seen a headgasket go so bad it was a group A version I have replaced it with another group A but the old one had split in two places)