[PontGuy]

You say that the builder saw that it was reading low on his gage right after he rebuilt the engine? If so then it really should have been resolved back then. Pressure on my engine suddenly dropped to levels like you are describing within 1000 miles of installation. I called the builder and he was just as concerned as I was. I pulled it right away, found the cause and shipped it back to him. He took care of everything including the shipping at his cost and was very apologetic. That was two years ago, and absolutely no problems since.

As for the cause- it could be a lot of things but the only way to find out is to pull the engine and open it up. In my case it was actually a pump issue, but probably more likely to be bearing clearances or some sort of assembly problem. I agree with others about using a builder with Pontiac-specific knowledge. There are a lot of local shops out there that claim to have the expertise but haven't touched a Pontiac engine for many years. They might have good intentions but if they don't have the detailed knowledge and you don't either then its a recipe for problems. My builder replaced the pump and also took the time to inspect all the bearings, double-check the valvetrain etc just to be sure that everything else was OK- he did not want it coming back again!

Just to be sure I would try another gage. Or if you have access to a calibrated gage you can also check yours against it on the bench using air pressure.