i have a chevy 350 small block that knocks at idling rpms. when the engine is cool, there is no knocking, but once it gets warmed up it starts aknockin'. once you get above idling rpms, the knocking goes away completely and the engine runs very smooth. the knock is pretty deep sounding and sounds as if it is coming from the driver side, in the very back of the engine. the engine also tends to overheat at high speeds regardless of a good cooling system.

any info would be greatly appreciated,
thanks,
shad