Today I was able to measure the front cam bearing journal AND the front cam bearing inner diameter.
Although I am not stopping here with my tear down, I do believe I have found the cause of the failure.
Here is my post #4 from this thread. I have eliminated everything but statements relative to the measurements I have taken today:
... I did find that I could rock the cam gear quite a bit.
Perhaps I should have been more precise in my words and included "up and down in the bearing".
The TM tells us that the
WEAR LIMIT for the ID of the front cam bearing is 2.434".
The measurement of the ID of the cam bearing in the subject engine is 2.440".
Combined with the wear on the camshaft journal this indicates a camshaft journal to bearing clearance of about .009'. The TM indicates that the wear limit is .006".
Although I have not stripped the engine to where I can measure the rest of the cam bearing clearances, I feel confident enough to say that 73m819 came pretty close. This cam shaft flexed over and over again in its bearings until it broke at its weakest point ... that squared off point just behind the first journal.
I would be willing to bet that the oil analysis will come back showing a high babbitt and copper content, indicating bad "engine bearings", but we will have to wait and see on that one.
The pictures I included in post #4 shows that the cam bearing was worn down to the copper ... there is no babbitt on the bearing