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a bad VOES would not, in itself, cause a bottom end knock.
all it does is retard the timing a few degrees to prevent detonation.
you can tell if you have a problem with the flywheels with a simple test.
with the engine at idle and making the knock, kill the ignition and listen.
if the knock continues as the flywheels coast down, you have a valve train noise.
but if the knock goes away immediately when you cut the ignition, you have a bottom end problem.
it is also simple enough to test the VOES to verify that is not your problem.
let me know what you find.