Prokek

So my car has a soft knocking sound coming from the engine. I recently replaced the cam chain guide. The car also has a miss fire, so I'm wondering if it could just be because of the miss fire or its actually a bad piston. I also checked the cylinder pressure of all 8 and they are all relatively close and in the normal range. Before i noticed the knocking sound the car had a stripped spark plug (I bought it knowing this) which made it impossible to hear anything else. The plug has been re-threaded and is now good. I'm hoping its something easier to fix than a bad piston. =/

Any help or advice is appreciated.

Frostbitten

take off the oil cap and see if smoke blows out