engine noise trouble shooting
 

so i landed a new jeep an 88 pioneer (gave it my version of a torture test) and just seems to be great HOWEVER on crank up it revs unusually high about 3500 rpm's to 4 grand (i hooked up a tach to it so i can see the rpm's) it sounds like a diesel running like crap. so i get out the ole stethoscope and listen to the bottom end and top end, it's almost the same sound as a bad rod bearing, knocking and all but the odd thing is i hear it from the top end much louder while listening with the stethoscope, i was 100% sure it was a bad rod bearing but now im not so sure the same sound comes while driving but go's away while accelerating but once i hold it at speed it'll be there but not as loud and when i let off the gas it stops, any ideas on what to check or how to check them? gotta do a rear main so i'll check the rods while im there for slop. would a dropped valve or bent valve make the same sound? thanks guys!

valves could do it but try your stethiscope on the passenger side of the engine and give your camshaft a listen, if it seams thats where it gets the loudest pull the timing cover off and check for slop in the cam, mine ran great but the cam moved in & out about a quarter inch. needed new bearings

oddly enough thats where i did...
 

check the sound at, i'll pull that cover today and let ya know what i find. thanks for the tip!
-happy