I was wondering if there's anyone out there who can tell me if the clatter I hear at 45 mph or 2000 rpm is cam bearings bad or if cam bearings would even clatter that way. I can say my oil pressure is low after it warms up. By the way, its a 400M. Someone please help me and tell me whats up.

 

I don't think bad cam bearings would clatter.
Bad cam bearings will give you low oil pressure but so will rod and main bearings.
I would look closely at excessively worn or broken rocker arms.

 

I just changed all the push rods. I know none of the rockers are broke. But I suppose they could be worn. The bad rods and mains make sense to. When I built it, I put a 3in magenet in the oil pan. Which was covered in metal dust when I recently changed the oil pump to. I will change the bearings to. The only thing is that its not a constant knock like that would be. But its worth looking at. Thanks for the info.