Oil Pump - Pressure vs. Volume

[Big Blue 72]

Just finishing a 390 rebuild. Everything runs great but I'm concerned the oil pressure is running lower than before. Runs at about 10-15 at idle. A mechanic friend who I highly trust with his knowledge of FE's recomended a high volume oil pump just to provide assurance everything is working fine. I've read all kinds of posts and the general consensus is stay away froma high volume and go with a high pressure pump. When I brought that up to my friend he said he wouldn't recomend it because I think he mentioned something about the pressure it would put on bearing seals, etc. I've read all kinds of posts about the subject and I'm completely confused. Some say leave it as is, 10-15 psi is fine. Others recomend a high volume pump, some recomend a high pressure pump because the high volume pump would rob oil from the lower end.

Can someone enlighten me on the subject between the benefits of high volume vs high pressure? Or should I just leave it as is?? I'm totatlly confused.

[fordman]

if you go with either pump then you want to restrict oil to the heads by putting a holley carb jet in each head. i think it only takes one per head. but i dont know fo rusre the size or how many.

[Big Blue 72]

He definately put the oil restricters in place. He feels there would be no harm with a high volume pump because it'll simply feed more oil to the lower end parts that want it. Seems to make sense to me....

[robroy]

Good afternoon Big Blue 72!

While I'm by no means knowledgeable with engines, I think your question's interesting and I have two comments.

First, I noticed that the 1972 Ford Truck Shop Manual, on page 21-23-29, states that the FE should have 35-60 PSI at 2,000 RPM. I know you're asking about pressure at idle so this might not help you much, but it's related at least.



Next, here's a video I recorded last Winter of Tom Lucas at FE Specialties explaining his views on oil control in FE heads. Perhaps it will be of interest to you.

The H.264 edition is high quality, yet plays only with rather up-to-date video software, while the WMV edition will play nearly everywhere.

H.264 (29MB) WMV (24MB)


Have a great afternoon Big Blue 72!
Robroy

[DuckRyder]

As long as it never gets below 10 at idle and rises into the range on robroys chart I would say it is fine. I would run a HP pump myself, I believe Melling calls it a "Cobra-Jet" pump.

[knightfire83]

If the engine he just rebuilt has lower oil psi than before, wouldn't that mean something has gone amiss in the rebuilding process?

The 4-5 engine I rebuilt, and even my old 360 I have now pretty much has steady oil psi around 25+ at idle. Even with a OEM pump.

Bearing clearances? Did you check them with plastigauge when assembling?
Plugged oil pickup?
Worn oil pump? Replaced?
Gasket between oil pump & block?
Leaking gallery plugs?
Pressure relief valve stuck?
Wrong oil?

Although it may be ok to run it now, what happens after the engine gets 10k miles on it and the psi drops further from wear? Maybe it's just a bad gauge?

[DuckRyder]

If the engine he just rebuilt has lower oil psi than before, wouldn't that mean something has gone amiss in the rebuilding process?

Maybe, maybe not...

Many folks open the clearances up on a performance build...

In addition to your list, I would take a close look at the cam and cam bearings

[Big Blue 72]

All good things to consider and I'm gonna pass it on to my mechanic. I know he changed the oil to a 20W-50 from the break-in oil he was using and it helped a bit. It's running at about 12 psi at idle. I know the oil pressure guage is new and correct. I think he'll end up installing a high volume pump for insurance.

[mrtleavitt]

I wouldn't worry about it. Stock pumps give enough oil unless you're pushing lots of horses like +600. I'm running about 400 hp with my 428, restricted the oil on my Edelbrock heads, running a cj oil filter housing, and opened up the oil passages, and everything looks great! Pops performance (a popular FE builder) says they always use stock pumps and they have some wild stroker FE engines.

[DuckRyder]

You can shim the relief on a standard pump to increase the pressure...a high volume pump will only give you more oil at 10-15lbs...

[averagef250]

I would recommend keeping the stock pump for any FE unless you are going hogwild 6500+ RPM with it. The stock pump is plenty, 10 PSI at idle is plenty, 5 PSI at idle is plenty. My opinion is if the FE makes over 25 PSI max pressure hot the engine's in fine shape.

The FE's live under different oiling rules than other engines, thier oiling system is different.

[cdeal28078]

I have heard about using Holley Jets more than once and always wondered about them. Seeing as how the jets are so small I would be concerned they would plug up real easily and cause problems.
I would think a new engine would have a little more pressure at idle but don't think it is a problem. More likely he just went on the open end of the clearances.
clint

[Dragon]

The jets won't clog if you have a filter. The Holley 80s I use in my daily driver if I have the head off will shoot oil about 20 feet on my truck on the passenger side. And the heads don't fill up with oil as high as they used to. Plus the boost in pressure the restrictors gave me quieted down my lousy wore out lifters.