I just rebuilt the motor (350 LT-1). I plastic guaged it to 2thousandth's on the crank. When I first start the motor, I'm at almost 40psi. When it gets warm it drops down to 20-22, and if it gets driven any length of time (city driving) it can get down to about 17 or 18. I have to rev it to bring it back to about 25psi. I am running 10w30 oil. I have 700 miles on the rebuild now. The car hasn't seen over 3000-3500 rpm's yet either.

I have never hooked up a manual oil presure guage. Any suggestions on how to do this? I assume I can get one from any auto parts store?

Thanks:

ZMAN

 

It sounds pretty normal except for dropping down to 17-18, but mine has seen around 20-19 after lots of city driving so you're probably alright. Might consider switching to Mobil 1 0w40.

I also resolved some WOT oil pressure issues by switching to a part number 1060R from Napa. It's a Wix racing filter. Not cheap at $12 but solved my oiling problem.

 

Hook up a guage to the plug above the filter in the block. Change oil to a heaver oil and a straight weight30-40-50 and dino oil. If ya have to go to a 40W to get pressure ya got a lot more clearance than ya think or your oil pump isn't right. Did ya put in a new pump?
Plasti guage isn't the best way to check clearance.

 

If you are referring to hot idle pressures of around 20 psi, that does not sound abnormal. You should be getting higher pressures at higher RPMs.

 

mine did the same thing with brand new everything. my bearings plastiguaged at .002 also. i ended up just haveing to use a little thicker oil now i have like 3000 miles on my engine and nothing bad has happened with the non synthetic 10/40 it does about 20-25 hot idle. also if you are using synthetic oil i have heard from a few people that synthetic oils are usually thinner than conventional oils. i have also been told the the GM minimum spec is 6 psi at 600 rpm but that would scare anyone i would think