-------PROBLEM NUMBER ONE-------------
For starters, my iroc is a 1985 L69 305 car. Cars gone through a pretty good resto, motor was rebuilt. The bottom end is all original stuff motor was cleaned up completely new seals etc. Q-Jet was replaced with a holley and it has a few bolt ons nothing out of this world.

I've put about 15k miles on the motor since its rebuild and for the past two years its been my daily driver with no major issues until now. The weather is starting to get hotter in Miami and as the car gets really hot like sitting in traffic the oil pressure goes from its normal high 50's (Which has always been its average) to about 30 psi and if its really hot sometimes even 15-20ish.

This has been concerning me cause the last car i had that acted this way was a poor abused LT1 T/A with almost 200k miles.

It normally only does this when its hot outside because at night its probably done it ONCE since I've driven it.

NOW... when the car is under load and cruising the oil pressure goes back up to the 50's. The second i hit the clutch it goes back down drastically.

What would cause this? Is this normal?

-------NOW FOR PROBLEM NUMBER TWO-------

Problem number two is that when the cars oil pressure is fine around 50 psi... If i turn on the A/C (which was all replaced with new components) the oil pressure drops to 25ish... and the idle fluctuates a few hundred RPM as the A/C clutch engages and disengages.

What could cause that?

ANY IDEAS would be helpful at this time, thanks in advance.

 

Sounds about normal.
did you replace the sending units with GM parts? Have you had the gauges calibrated at a rebuilding place? The camaro gauges are known to be off quite a bit..

 

I forgot to mention that the voltage guage reads lower instantly when i turn on the A/C.

 

that all sounds about normal with an l69 car, mine does all of that too, only my oil psi gauge has been messing up and pegging itself sometimes.

 

How many miles on the stock bottom end? What weight oil do you run? You state that you didn't rebuild the bottom end or replace any internal parts. As the bearings wear, which is normal, the oil clearances increase so that the original oil pump has a hard time pumping the 5w-30 fast enough to maintain pressure in the increasing clearances at idle speed.

One thing to consider is stepping up to a heavier oil like a 10w-40. The 10w-40 will maintain higher hot oil pressure without causing any valvetrain oiling issues with the stock pump. The factory Q-jet had an idle speed actuator that bumped up idle to compensate for the load placed on the motor by the AC compressor. I'm thinking the Holley doesn't have this. Unless it's a Holley stock replacement carb. In which case, you may need to adjust the actuator to increase loaded idle up a little. Otherwise, the lower idle with the AC on is just how it goes. That's why GM used the actuator.

 

That makes a lot of sense with the q-jet... That may be a possibility im gonna look into rebuilding my q-jet. My the bottom end was fully cleaned up and all seals and bearings were replaced i just don't remember if we replaced the actual components like the rods and crank.

 

I am having a similar problem but my oil pressure sky rockets only on the highway or under really heavy loads. I am also running the L69 HO my motor has 120k. I run a semi synthetic 10w-40. Im just not sure if the oil pressure swith is going out or if it is correct.