340 Engine Shake

512Stroker said

Strange you dont see any drill holes in the crank counter weights.
Most balanced crankshafts will have material removed from the counter weights to balance out the assemble. The machinist will use a drill or an end mill to accomplish this and the marks are very visable.

Click to expand...

I saw that also. there is one drill hole at the very rear, but you are correct, there are usually a few more.. I have a 340 crank on my bench right now, OP if it will help I will post a pic later. It may help to see how a internally balanced crank is drilled...let me know...