1995 lantra J1 misfiring
 

Hello,
I have just cleaned the tappet cover gasket up to stop a leak just below the head and my 1995 Hyundai Lantra J1 has been running very poorly since, It sounds like it's misfiring and i was hoping someone could tell me how to check the cam timing as I think it may have moved when i loosened to head off. I did not take off the cams for this, but i think they may have moved when i lifted the head up.