The "key" on the bearing shell is not all that keeps the shell in place in the rod.
A properly sized/finished rod big end bore is smaller than the OD of the bearing shells resulting in "crush" of the shells when the cap is installed and tightened--this also REDUCES the bearing ID to the proper size for the selected journal size. When crush is reduced the bearing/journal fit is made looser-also the shell is not secure in the bore and will shear the key and spin the shell destroying the journal because the oil supply is cut off.
A bearing that has spun in the bore destroys the dimension as well as the smoothness of the bore, and since the soft part of the shell takes the shape of the steel back and supporting bore,now the part contacting the journal is not uniform.
Even small particles trapped behind the shell at assembly cause a high spot in the soft layer contacting the journal and can cause premature failure.
The size/finish of the rod big end bore is CRITICAL to bearing life.
Question : why are you so opposed to pulling the head/piston/rod to make this one right?
That's a good explanation of it, thank you. The answer to your question is pretty much the only reason I'm even trying this. I've had to take the engine apart so many times, and I'm on a deadline now. There is only one engine shop in town, and I had a lot of trouble with them turning my crank. They kept telling me it would be ready 'tomorrow' and every time it wasn't. I even went on a week long trip to NYC and when I came back it still wasn't done. All in all it took them three weeks to grind it. And since they're the only place in town that does it, I just can't wait that long to have them do what might end up being sub-par work. Plus I'd have to wait for gaskets to be delivered on that head gasket. So I guess that's the main reason why. To have it done right, we're talking weeks of time and possibly sending it out of town to another machine shop. But that may be what I have to do.
Jerry: Hey, sorry if I came off as arguing. The advice you guys have given has been great, and correct. I never disputed that fact, I just wanted to make sure I got all the info I could to make sure I was getting the whole picture since I don't know what I'm doing. I'm still unconvinced my way will work at this point, but because I have to get this truck rebuilt and off this property in such a small time frame, it's putting me between a rock and a hard place. I'm gonna stop and take a thinker, and maybe do some more research before I do anything drastic. Maybe I'll get lucky and find another machine shop in the area that isn't listed.
