I had that in my 164 at 204,000 miles and thinking it was rod problems put
in a different engine. When I finally tore it down and plastigaged and
miked it I found the following:
Zero measurable wear on rod bearings
Zero measurable wear on main bearings
less than 0.005" wear on the worst cylinder
Could have used a valve job
Bad fiber timing gear.

I suggest you try a timing gear. Lot cheaper than an engine change.
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George Downs Bartlesville, Heart of the USA!

Knocking, as in mechanical clunking or as in ignition pinging?

The timing gears are the achilles heel of the B18/B20 motors, I think often the B30 got a steel timing gear set but it could still be the culprit. At idle and low speeds a bad timing gear can sound like an idling semit truck diesel motor. It can sound just like a rod knock, only a timing gear will often quiet down as the rpms rise, but rod knock can happen at any rpm if the piston loading is right (often when the rpms are falling, on the 'overrun').
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I'm JohnMc, and I approved this message.