Your bearings have nothing to do with engine knock. Knock is caused by premature detonation, when the air/fuel in your cylinder ignites before it's supposed to. This is caused by a faulty EGR, bad air (dirt, deposits, PCV/recirculation gunk, dirty filter, obstructions), bad electronics/ignition (distributor worn, timing off, bad plugs/wires/coil/distributor), or bad fuel or fuel filter. The worst cause would be a contaminated combustion chamber, which means your heads/block have accumulated so much gunk and carbon that it's retaining heat and igniting the a/f mixture. Change your spark plugs, check your plug wires/distributor, check your air filter. Also, add some fuel injector cleaner and some octane booster from your local auto parts store.