Also is the car over heating? and what weight oil are you running?

I am running 10W30 Valvoline oil and PH8A Fram filter.

Both were changed in November and car has run about 100 miles since then. I experienced this issue last summer as well when I took a road trip on the old oil and filter.

It does not overheat. Runs steady dead center of the heat gauge even after coming off highway. I am running 24 inch rad and a 180 degree thermostat. Gauge only ever spikes briefly on a hot startup, until coolent flows to carry away the stored heat, then settles right back to the middle.

My oil gauge just has the range, no numbers. Runs steady in the middle during driving and normal idle. I would say it drops to the bottom of the range on stopping from a higway run at idle. Not quite zero but sometimes close.  Picks right up again when I start driving once more and returns to the center. If I ease off to a more gentle stop from the highway as opposed to letting the rpm's drop suddenly right to idle, it seems to help reduce the pressure drop.

Engine had a front sump pan put on to make the 5.0 liter fit over the 68 crossmember. Unsure what
pump and pick-up were used. It is a 4 barrel carb set up with an electric choke. It is an original roller engine.
 

I have had hydraulic roller lifters make a ticking sound.  It will tick real loud and then go away.  Not saying that is how it should be, but have had it happen, and upon teardown found nothing wrong.  One bad thing about roller lifters is they do not rotate in their bores like flat tappets do.  I think that can create more wear in the bores.

I would not be too concerned about the oil pressure issue.  If you have good pressure going down the highway, the pump pickup and oil pan clearance are obviously just fine, and you have plenty of oil in the engine.

If the noise perisits, I would probably pull the intake and check every lifter.  6sally6 can attest to what happens when a roller lifter fails.  Basically you tear down the engine to remove all the schrapnel.  Better to find a bad lifter before that happens.  The Ford 5.0 roller lifters are known to be nearly bullet-proof, and rebuilders will often reuse the old ones if they look OK.  I did that on Cara's 65 5.0 engine when I rebuilt it.  It did not make any noise.

Before you tear totally into the intake, I would check the valve adjustment, if it has adjustable rockers.  If you have one with a little extra clearance, going down the highway might have enough oil pressure to keep the lifter pumped up and tight, but then at low RPM it may develop the gap due to lower pressure.  If you are using pressed in studs, lay a straightedge along the top of them to see if one is a little longer than the rest.  That would indicate a rocker stud pulling out.  If you have the later 5.0 heads with bolt-down rockers, all you can do is check to see if the bolts are tight.

Doesn't tell me a thing! Looks good,really.
I'm betting the bearings are worn...or a pump going bad. FoMoCo are famous for running low oil pressure. 40 or even 20psi is normal in most cases. My 289(before engine swap0 would go to zero at warm idle! Drove it that way for years! Try thicker oil.
6sally6

Last edited by 6sally6 (5/06/2013 5:07 PM)

Looks pretty damn dry ???....jj

Thanks for all the input. I think I will try heavier oil to see if that keeps the pressure up top when I come off higher rpm's.

Photos appear dry as they were taken after rebuilt and engine sitting unfired for a long time. It had not been fired up at this point. I swapped out the intake before ever running it for the first time.

Pored some oil down each head before initial fire up.