[Alan Roehrich]

You don't need roller cam bearings. I wouldn't run a 50MM cam in a big block.

Note, I've edited this post for clarity:

I meant to come back and clarify this, as I answered it "on the fly" or "off the cuff".

Stock core diameter is adequate for most applications. Comp calls that a 1.948" core, and does not give a "MM" dimension, however some research and conversion to metric dimensions yields 49.47MM as the dimension for a stock diameter babbit bearing 1.948" core.

A 50MM (actually 49.98) core is actually 1.968", which most cam companies list as a "stock diameter" for use with roller bearings. That is where the confusion here comes from. From what I've seen, the industry standard for core sizes refers to the actual stock diameter big block Chevy core as 1.948", and the "stock core diameter for roller cam bearings" as 1.968, or 50MM.

I'm actually surprised one of my friends didn't send me an email or a private message and bust my chops on it.

I certainly should have been more clear, and more careful. I hope this resolves any confusion here.