Oil Pressure keeps dropping!
 

I just rebuilt my 454 (.30 over = 468), put in a lot of new high performance parts including a melling oil pump. Got the engine in the car, started it, set the timing and let it idle for about five minutes, during this time I noticed the oil pressure gauge needle start dropping from 70 psi to 20 psi. It seems as soon as the engine gets warm the pressure starts to drop. iT HAPPENS OVER AND OVER. I changed the oil pressure gauge to see if that were the problem, gauge works fine. Put in sae 50 weight oil, pressure still drops.

SOMEBODY PLEASE TELL ME THEY HAVE HAD THIS PROBLEM BEFORE AND KNOW HOW TO FIX IT!

a new engine will show high pressure, 70 cold is high in my opinion.

but can you be more specific here,
Is the pressure 20 at idle HOT ?
Does the pressure increase as you rev the motor?
What is the pressure at say, 5000rpm?
Does the pressure drop as you rev the motor?
Who built the motor, could be clearence on the loose side for bearings?

do you have a good running carb on it? it could also come from your carb putting gas in your oil thinning it out.(even with gas in your oil, it will read at an high psi on start up.)

Try installing a delco oil filter? Have seen this many times.

Are you using a FRAM filter? I have lost oil pressure like what you are talking about,and i had a FRAM filter on the engine,changed that to a NAPA and problem gone.

Mine holds about 60 idling cold and in the garage it drops to about 50 after it warms up to like 180 or so. But at the track after a pass it drops to about 40 idling until it cools for a few minutes then it is back to 50 idling..I have ran Fram and what I try to use is a Wix oil filter..

A drop in oil pressure at idle as the engine heats up is normal. What you should be concern with is if the oil pressure goes back up as soon as you rev it a bit. Different engines react differently. As long as you have good pressure when not at idle and the pressure is stable and never gets below 20 psi at idle, you'll be ok. This is a common problem on engines that have grooved bearings or the oiling system has been modified by making oil passages larger. Maybe even if the crank has been cross drilled or grooved. Just to be safe, remove your oil filter and open it up to make sure you don't have metal particles in it. If you do, it's most likely babbit from your bearings. You will have to take your engine back apart and check it for clearances and damage to hard parts. JMO George

Change the oil filter :!:

X2

Filter
 

X3 If you have a Fram, chuck it and get a Delco K&N or Wix. Read another post about the Frams.
It's under General Discussion "DON'T BUY FRAM OIL FILTERS !!!!!!!!!!!"