I've been making knocks go away or at least have a major reduction in noise for over 50 years by shorting out spark plugs. Cracked pistons and loose wrist pin bushings are the most common knocks that change when a plug quits firing, but even a rod knock will reduce a bunch with no combustion load applied.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!