There is also the possibility that one or more oil gallery plugs were not put back by the machine shop when the block was cleaned. When that happens the oil pressure has no way of building up.

 

Ooh, that's another good thought too Pete. What gets me, is that the machine shop guy is stumped!
Is he only accustomed to working on lawn mower engines?

 

Makes one wonder. Maybe the "regular guy" was on vacation. Silly as it may sound, I saw a guy install a high volume oil pump trying to make up for a missing plug.

 

Heh...heh...that's what JB Weld is for! lol
This guy's issue has to be a simple oversight of one of the above. Problem is, the simple thing that was missed now makes for a big time consuming task to fix. There's a word for what happened, what is it. Oh yeah.....oops!

 

The obvious question nobody asks is what is the oil weight/viscosity, and have you tried a different oil, such as the 5W-30?

 

While that question is valid on an older worn motor, with a newly rebuild motor even kerosene should get 15-20 PSI.

 

new/rebuilt ls1 should have 60lbs with 5w20

 

i lold