I noticed after taking my 86 Camaro to a show yesterday that while I was coasting at low speeds or put my car in neutral a knocking sound would come from underneath the car. The oil pressure is fine. I can only hear the noise when I am coasting at slow speeds with no load or when I put the car in neutral sitting still. The knocking increases in tempo as I increase the rpms. It doesn't do it all the time. The noise is there only after driving the car for about 30 minutes.

1986 Iroc with a 1974 350 from a police impalla. Has the TPI setup off of the 86 305. I have no idea whats been done to the internals on this engine. From the looks of it its the stock 74 block from the impalla.