[lust4speed]

You can take a pump and completely block the flow of oil, and the pressure will be whatever the pump bypass (with that weight of oil) releases at. I have test spun oil pumps up by bolting them in place on a spare block, and attaching a remote filter plate with hoses, pressure gauge, and valve to close off the oil flow after the pump is primed. This has always given me the maximum pressure the pump will produce in the final installation. You can't get over 100% restriction so I wouldn't believe the quoted paragraph saying that different engines might produce more pressure. Therefore, tight clearances do not have anything to do with excess pressure. Loose clearances will of course bleed off enough oil so the bypass never has to open. Les' engine was also set for .0025" clearance and even with the 20w50 oil the pressure was only 82 pounds with the engine at operating temperature. With the lighter weight oil he has now, the pump is performing exactly as per the Butler specs.

Did you check the oil pressure with a back-up gauge? I'd do that first, and if the second gauge also reads 100 lbs., then I'd return it to Butler for warranty replacement.