Nissan Repair: nessian sentra, nessian, sentra

Question
I'm getting a nocking noise from the passenger side of the engine under the valve cover.97 sentra

Answer
Hi Stephen -

Is this noise a low sound, or higher pitched? Does it happen only under acceleration, or all the time? How long has the sound been out? Have you changed grades of fuel lately?

Any info you can give me would be great -

Thanks
aloha\
calvin