Jan 18, 2007 · "Knock"—an unregulated explosion in a chamber designed for highly regulated combustion—is the bane of an internal combustion engine. During the four-stroke cycle of a typical car motor, the ... Rod knock can also be eliminated by pulling the plug wire on the offending cyl. So being you have a 93 L05 350, you can take some spark plug pliers (insulated!!) and pull off each wire on the cap while it is doing it one at a time momentarily and it will identify which cyl and if lifter/rocker knock, it won't go away, if rod, it will go away.
chevy used an ingenious nylon toothed cam gear that can wear enough for the chain to slap the block, and it can sound just like a rod knock. i had one do that, with the stethoscope it sounded like a bad rod in the #4-6 area, and it was just the gear missing a couple of its nylon teeth. This is a great idea. I was never a believer I additives either until I added a qt of lucas oil treatment to a ford 300 6 cylinder. These are known for a dry knock on cold starts because the oil drains out of the filter and back in the pan overnight.