Join Date: Aug 1999
Location: Ontario, Canada
I once had a loud knock from the engine, only at certain RPM and conditions, swore that the crank was out of it, even had 2nd and 3rd opinions, Yanked the mill out of the Camaro, flipped it over, pulled the pan, started to check individual rod bearings, then when I grabbed the flex plate to roll the engine over I found that the flex plate was loose to the crank, ARRGH !!!! wasted that weekend.
To pin point your knock, pull one plug wire at a time, if the noise is less then you have found what cylinder to look at, another thing you could be running into is the piston slapping the top of the head, would be most noticeable at high RPM with little load.
Lifter or valve train noise would be a light tick noise where the bottom end is a knocking.