Generation IV Internal Engine - Oil pressure ???????????????

I just had to replace a crank keyway on a new engine 418 stroker ! It broke bent few valve anyway !
I had to remove oil pump to replace the keyway DUH! But here is weird thing !
The oil pressure when first started is 35 ish then dropped to 17 ish then as i drove around and came to a stop light ( using hp tuners ) I watch the pressure go to zero then .01 the 0 so pulled in at zone replace sensor right there connector was little oily wiped down much as i could ! Refired car 22.8 lbs then drove around its between 15.9 and 22.7 idle and 2500 its 38 and up as rpms increase ! At wot its a 62 psi !
What is going on here > I have 15/40 in motor with two quarts of trick flows break in fluid !
IS THAT THE ISSUE ?
SENSORS WIRES?
PO521 IS CODE AND ITS SETS IT AFTER IDLING FOR FEW MINUTES
NOT A HIGH CODE OR THE LOW CODE 522 OR 523
IS IT OIL?
ADDITIVE I PUT IN ?
PONTIAC G8 418 LS2 STROKER

When you installed the oil pump both times, did you align the gear and housing or just bolt it up and go?

I would check it with a mech gauge but don't run it more than you have to.

Never heard of a keyway failure.

What kind of rod and main clearance do you have.

Tim

The key broke and it bent valves and you just replaced the key? Typically to break one of those there has to be a point of high resistance in the motor somewhere? (possibly a valve to piston clearance problem?) It could be the oil pump itself which is why it has crazy oil pressure now? The oil pump may have also been damaged when the key broke.