strange sound in engine

[paul cass]

hi everyone
where has the time gone. here it is almost june! anyway, been real busy with tennis and cars.
got a question for the small block experts. put a rebuilt roller 302 in my daughters bronco. about 3000 miles on the engine and its developed a slight knocking noise in the engine. the sound is more like that of an exhaust header leak and seems to be coming from the right front of the engine. its not very loud. very difficult to hear when engine is in park. in drive under load the noise seems to get louder. sound doesn't seem to be coming form the valve train. drained the oil thru a filter and found no metal or debries. checked the oil and there was no trace of metal or coloring that might indicate a spun bearing. checked end play on crank and was within tolerances. checked distributor gear and it looked normal, no sharp edges. she's visiting over the weekend and i'd like to fix the problem before she has to leave. help!!!!!!!
thanks,
paul
ps several engine people have listened to the engine and agree it doesn't sound like a rod bearing or wrist pin, especially since there is no metal or color in the oil. i really don't want to pull the engine and disassemble. a