I replaced a set of rods in a 6.0 motor, and the set that came out of the motor have this "notch" or cut-out cast into the edge of the rod - for more oil I guess. The replacement set didn't have this notch. I have a slight vibration now, could this be the culprit? Thing is, I made some other changes (new converter, flywheel) all about the same time so I can't just pin it on the rods right off the bat.

 

I really have a hard time believing that that little 1-2 gram notch would cause a noticeable vibration. Even figuring 2 rods on each journal at rpm doesn't seem likely as the factory balance job is probably only within 15-20 grams from "dead nuts"....even the weight of the oil on the parts is a variable at all times. I'd really look into that flex plate/converter set up.

 

I had to open-up the flexplate for the smaller 9.5" PTC converter. I tried to dremel open the holes evenly, but there may be a little bit of difference at each hole. Could this cause an issue? Seems like a small amount of metal either way.

But back to the rods, I should of weighed the old vs new, who knows if there is a difference that I wasnt aware of.

 

the converter once filled is pretty heavy that if it's just a smidge off could vibrate quite bad at engine speed. Is it really noticeable at idle and then you don't notice it at high rpms or just the opposite....worse with rpms ???
Only if the big end weight of the two rods differed by say 10-15 grams would it be obvious

 

Seems to be noticeable really just off idle, around 1600-1800 then clears out. Otherwise it feels ok. Def not as bad when rpms go up (thank God!).