Originally Posted by Hubes
Im not going to be pulling a lot of rpm so maybe Ill just take it to a machine shop and see what they think. so do you guys think its zero balanced even though it has those 2 holes drilled? its just 2 holes beside each other about 3/8 diameter and probably about 3/8 deep. thanks
As previously stated, the cracks are most likely heat checking, most likely from using the clutch as a torque converter, the part way in but not quite engaged makes for a lot of heat. A very good reason to develop a good heal toe technique for launching on hills.
For the holes, there are two possibilities. The 350 is internally balanced from the factory. The holes in the flywheel could be to get it to neutral balance by the factory, but the factory's idea of balanced is a wider band of goodness than the typical hot rod shop's idea of balanced. If this is a balance shop job it could be what was required to re-balance the wheel to their specs at neutral balance, this is pretty common. Or the entire rotating assembly could have been balanced and the flywheel and crank assembly are now a matched set. I really wouldn't expect this to be the case but it does happen. It's really not to difficult to see if it's neutral balanced, just support it in it's mechanical center to see if it sets horizontal to the earth, something like a bubble tire balancer will also work.
One last word about dynamic balance where the wheel would be spun. This method of balance is in 3 dimensional space. The wheel would not only be balanced in rotation, but also in plane at what's called the normal direction to rotation, which is to say thru the thickness of the wheel where an imbalance would cause it to want to wobble front to rear as well as spin off center.