The sound is definetly a lower end noise, constant low frequency "drumming or rapping" of the crankshaft which does not go away till engine warms up. Remains constant does not increase in intensity (or stop) with increase or decrease of rpm's. (like a rod bearing failure normally does). Valves are adjusted (hot to specs), no clatter there. I was told that these babbet bearing engines are notorious for noise because of the reduced lubrication efficiency of the splash oil system. (IE: Thus the nickname "BABBET BANGERS") True? False? If not, I guess it's time to break out the mechanics stethoscope.
