Hello everyone. Long time Reading, First time Poster!

I'm running a 1971 Lincoln 460 block, And its having some Oiling Issues. Before I get to that, I'll explain about my rig, and what happened in the first place.

My rig:
F-450 Frame
Jeep Body
460-c6-205
Rockwell Axles (front steer, solid rear) on 47" LTB's

What happened:

Over time, wheeling with the rig, Lots of jumps, bumps, and general thrills while mudding. The problem that i didnt notice, Was the raise center Chunk of my Rockwell front axle has a top plate cover, which one of the bolt heads had been tapping my oil pan. one day while wheeling, I hit a bump hard enough that it punctured through the oil pan, shooting all my oil out. With full Hydro steering, I had to leave it running, but in neutral, ans my buddy quickly (2 minutes) pulled me to his shop.

Upon inspection, Piston walls were still perfect, Head components were fine. The Main+Rod bearings had gone to the copper layer (mid of the 3), however the crank+rod surfaces were still perfect. So i went ahead and changed all rod+crank bearings back to 10 over. Swapped in a High Volume Pump, and a new timing set while i was there.

When i reassembled all of it, Fired right up, ant at 75-80 PSI.

But heres my problem: At about 5 minutes of running, even at idle, It drops to 60 PSI. 10 minutes, 40 PSI, and so on. It still hasnt dropped below 5 PSI. When i hit the gas to about 2000 RPM it always perks up 20-40PSI. WHile i've been told that 5-10PSI is ok to run, Its seriously bothering me, as the Chiltons book says the block should run 60-80 PSI at 2000rpm, and around 40 for Idle.

What could be wrong that it starts at 80psi, and drops? Only possible ideas i've heard were cam bearings. Fresh Oil, break in lubes for all the new bearings, flushed everything out, kept it all clean and immaculate. So i honestly cant figure it out, and would GREATLY appreciate any advice!

 

So far i'm hearing alot of people say Cam Bearings. Anyone else agree?

 

No on the cam bearings, at least not likely. If you have a Fram filter on it try another brand. Without actually checking the bearing clearances with a good dial bore gauge that reads in .0001" & a set of mics there would be no way to know what real clearances you have. I'm no fan of plastigage but it could at least let you know you need to tear it down and inspect the crank. The block's align bore and rod bores for round, straightness, size. This all started when you lost the oil ?

 

The pressure valve on the new high volume pump could be stuck open. Drop the pan, take the valve apart and inspect the check ball and bore before you get to freaked out.

 

I am going to disagree with mark here.

If you damaged yoru rods and mains from loss of oil there is a very good chance you also damaged your cam bearings too. Should have at a min been checked.

might want to check your lifters also and make sure that the lifter bores aren't damaged.

 

I'll agree with everyone on the cam bearings because you ran it out of oil, may have even spun one. But here's the thing, if you installed a new Melling HV pump, they're actually known for having this problem. Had it happen to me and learned this the hard way. Rust inside the pressure valve on a new pump, Yep, I said rust. Steel check-ball gets jambed when it opens and can't re-seat. Good pressure at first, then it keeps dropping. Always supposed to dis-assemble and inspect before install. School of hard knocks, been there a few times over the years.