ticking noise on 700 mile fresh rebuild

[evan-326]

i have a 2000 ford ranger xlt 4.0 v6 4x4 i did a fresh rebuild about 700 miles ago it has new everything except the following, block, pushrods and the rocker arm assy, plenum, injectors. The ticking noise will start on a cold start and it sounds very loud, it goes faster with rpms, sounds like a sewing machine, it only goes away after it goes to half temp then it runs and drives and sounds amazing. used a mechanics stethoscope on everything sounds the exact same which leads me to believe its in the middle of the block. if there is anything you guys need to know please ask, i really need your guys' help and opinion on this.