Unless the
"race engine builder" has/is been taken out of the mix I'll bet he wants to disassemble the engine. What number cylinder did you loose and has
oil system been modified for increase and decreased
oil flow in different areas.
Rod bearings tend to go south in pairs or common crank throws because they have the same
oil supply and other than rod bearings have the same clearances. The radius of that crank throw should be inspected closely as well as rod pair side clearance. The rods should have been checked for twist and being bent when recon'd but double check for sure.
Loosing a rod on start up or break in just about has to be a clearance issue as mentioned already. Crank pin diameter is probably correct if the bearing on the same throw is OK. The rod bearing insert will often turn in rod if not torqued or left loose and rod will often knock before spinning insert. The crank pin and bearing will show you what was wrong. Photos of each will help us back seat drivers form a few opinions. Let us know what you and your builder find went wrong.
You did say you changed the oil and fired it up the next day, never lost oil pressure. After oil change was start up pressure verified for sure? How long after oil change did it run before knocking? Was the common rod bearing good, you mention crank pin was good? Were the rod bolts tight? What hole went bad? Is your last name Murphy?
My
swag is the rod bolts for that hole was not torqued
if the rod on the same throw is good. Keep chin up, it will only get better.
Threaded Mode
