I have went through the same scenario even using different builders. The issue was the bypass valves. Non marine guys can build a good motor and ruin it by putting in the two 11lb valves instead of a single 35lb valve. The last go around I plugged them off. We'll see how this set of engines lasts.

the mercruiser parts drawing shows the cooler after the filter the teugue marine shows it before the filter

This really doesnt matter, but if I was you, I would make sure as someone else asked...that there are NO EAGLE parts being used and then the second thing I would do is find a better "reputable" builder. In my thinking, there is no excuse for what you are dealing with on this motor...especially if they have had to go back and mess with it 4 times.

i agree the eagle crank journals are all over the place,but i use a lot of their h beam rods,and they are on size,somebody is doing something wrong for these failures to keep happening,also,.002 is not enough clearance for a bbc marine engine.who is doing the assembly,you or your machine shop?

No the machine shop is doing the assembly, please let mek now what should in your estimation or expertise should the crank and rod bearing clearances be?

What brand crank are you using? Also brand bearings and type example: "P", "H"

i use the h bearings and run a min of .0025,for bigger power ,.0028 to .0032.

And the most important is when he installs the rod bolts and if he is using new rod bolts everytime he needs to stretch the ROD BOLTS first or they will come loose then the engine will start knocking..
Does he use a rod bolt stretching gauge ??? or does he even know..

I would look into what you're doing with the bypass valves. You need to be running a 30psi bypass, if you are running a external cooler/filter adapter, which I am sure you are. using the 11psi ones, not only are you probably bypassing the filter, you're also bypassing the oil cooler and main galley.

The bypass, in the center behind where the filter would thread onto in the block, goes directly to your main oil galley(return feed). If your bypassing your main oil galley, I can see where your problems are coming from. The other bypass (next to that one) is the oil filter bypass. Use GM#25161284 30lb valve there, and remove the valve in the center so the oil will flow directly to the main galley after its filtered.

find another engine builder...something is very wrong