Oil Pressure Dropped...

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unapez

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I dropped a completely built 360 in my 72 dart, with lunati bracket racing cam and edelbrock intake. I have a high volume oil pump. When I started it I had 75 psi oil pressure. Drove it for several days and realized that my system was out of balance and I needed to go more mild. I removed the racing cam and installed an RV torque cam, new lifters, and changed to a stock 360 intake manifold. I started it up and now there is about 10-15psi at idle, gets to about 40-50 at high rpm... what happened?
 
Had the same thing recently on my rebuilt 340, oil pressure was good for a few days then dropped off.
All my main and rod bearings are shot, crank is in a sorry state, cam bearings gone as well, also had a HV oil pump with stock pan.
All this happened in 350 miles.
Ironically the cam lobes are still in great shape.This engine sat for 3 years after rebuild and in hindsight it was very hard to crank over when I was priming the oil system, 1/2" flex bar but still tough to turn.I have it in pieces but still can't see what caused the problem, I am now guessing it was built too tight, had 0.010" undersize bearings in it, maybe wrong but can't tell as the crank is to bad to get a good measurement.
The oil pump was also shot, if I were you I'd drop the pan and pull one of the bearing caps just in case, only takes a couple of hours as long as your steering isn't seized.
 
Was it 75psi the last time you drove it before changing intakes? Or did it drop a little before? What intake gaskets were used, and how much silicone was present to remove? Did you also replace the oil and filter after the cam break in period? Were the oil filters the same exact brand/model?
 
changing the cam and intake should have no effect on the oil pressure. Something got futzed.

Not saying you did this but ? A long time ago a buddy of mine used a ton of silicone when he built his motor, well, after a couple miles the oil pickup got clogged with cured silicone worms, and dropped his pressure.

Could be a problem with the pressure relief valve in the pump as well.

I'd drop the pan and inspect it.
 
Odd that I saw this post, as I was just going to post something similar.

My engine is a few years old, has maybe 2000 miles on. Car runs great, starts easy, etc.

It always ran higher oil pressure also (70-ish @ 2000rpms hot). Recently I changed to a 10w-30 from 10w-40 oil, and also put in roller rockers (had non-adjustables). Now it's only running about 40psi....ever. Even at 3-4,000 rpms it stays at 40psi...I have a stock pan with a windage tray welded in it.
 
Assuming all else is equal (no trash in bearings) I would suspect the new cam has slightly undersize journals, or the lifters are undersize. Neither are typical problems however (unless your engine had .008 OS lifters from the factory).
 
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