"Clunk"

One of my high time motors developed an annoying clunking noise at idle. It reminded me of a rod knock but the sound would completely disappear above 2100 rpm's. The noise turned out to be caused by a small amount of wear on the ends of the rocker shaft. ( where the engine tilts) About 1/2 turn on the nuts on the ends of the rocker shaft and the clunking went away. It made the noise only at idle because at low rpm the whole engine would slide back and forth on the rocker shaft. While you're checking those nuts tighten up the bolt on the steering plate also.