I don't have any bad experiences with machinists. They are the bread and butter of my business. However, I understand their knowledge of turning metal and I respect their input on how to complete a given task using a lathe or a mill. When they start to put forth engineering opinions on things where they have very limited experience and data, and no formal training, then I thank them and tell them that I'll seriously consider their idea.

Fire away. I'd sure like to find the answer to the rod bending issue. However, any answer must address why the 603.961 very rarely suffers from bent rods whereby the 603.970 and 603.971 engines have the bent rod situation all too frequently.
The engines are nearly identical in most respects.