Has anyone stopped to think that maybe the actual cam bearing journals are too small? Did you measure the cam journals on your old cam vs. the new one you installed? If it's off even 2 thousands I can see that being your oil pressure loss. You can install a new gm high volume pump for $80 or measure your stocker and yank out the aftermarket one and compare. I don't like low oil pressure in engines.

 

+1, It's probably a size difference in the camshaft itself where there's more clearance between the cam and the bearings.

 

Yea, I did, a few posts up....

 

Yea, there it is...missed that somehow, sorry...

 

Did you remove the oil pump in order to change the timing chain? If so, check your pick-up tube o-ring. If not, you are probably looking at changes in clearances.

 

Yall are running low pressure, my 01 idels at 50psi and runs 75 - 80 at WOT