For awhile, after an engine rebuild, I was getting some false knock @ 2000rpms due to a new cam & distributor. Bought a K&N knock sensor setup, installed their sensor in an unused 3/8 x 16 hole near the thermostat housing in the lower intake. Their adapter is a 3/8 x 16 stud w/ a 1/4 NPT female fitting on the other end. The K&N seemed to read the *real* knock correctly, but ignored the false knock - probably coming from the cam / distributor gears. Removed the K&N system & remounted a stock knock sensor in their adapter - seemed to work fine & the ECM didn't hear the false knock. After a few thou miles, the false knock was gone (checked w/ stock mounted sensor), but I left the sensor in the manifold - hell of a lot easier to get at.
FWIW, YMMV, etc.....