Heh there's a limit... I didn't bother checking that main clearance but it's gotta be huge... it vibrates horribly at 4k+... enough to warrant pulling the motor

I wouldn't think your extra clearance on your #5 would cause a vibration. Your oil pressure should cushion that. Did your oil pressure change when the vibration start? All your bearings (even your rod bearings) looked scrubbed to some degree. I just took apart a 1976 440 that had original bearings in it. The 440 bearings looked better than any bearing in your pictures. Maybe a vibration damper failure? Lack of oil pressure? I agree with the larger clearances as well, unless your running 0W20 oil, in your non-performance engine. Just my

It's definitely the source of the vibration, and yes oil pressure dropped

You added extra clearance. How did you do that? It's "huge" but you don't know what clearance it has? But you are sure it's your issue. You took the time to take it all apart. Then made a change and didn't measure anything? Crack check anything? Put it all back in the car. Uhmm.
Doug

I mean come on, you find a massive wiped number 5 main and you're not going to attribute it to a high RPM vibration?...

And actually yes I did mag the block and the crank, I found a good deal on a 331 stroker though so none of that is going back in the motor

Are you going to measure the clearances on this one? BTW, what bearing clearance does ford recommend?

Yes just like I did the last one.

Is this car m/t or a/t? iapco103

manwell

These engines have several variations of flywheel , I suspect that the one you have is incompatible with your crankshaft and this is the source of the vibration and bearing wear.

Finding the correct one can trying at the very best. You will need a very patient FoMoCo parts man to help you.

Best of luck , iapco103