Hello,

I have a question about oil pressure and FE fords, I have a 76 f150 with a 390.
At the moment it has 15 psi at 700 rpm hot. It will go to 40-45 psi at 2500 rpm.
The cold pressure is at 55-60 psi. I have no knocking or engine noises and burn about 1 qt oil in 2000 miles. I use Castrol 10w-40
I belive the readings are a result of the main bearings, My question is how bad is the current oil pressures as I have to use this truck daily towing a trailer, And has anyone had any luck with dropping the pan and replacing the main and rod bearings on these motors.
I will be rebuilding but would like to make it a while longer.
Thanks for any information.

 

Those numbers are plenty good.

10 psi per 1000 rpm will keep everything happy under all but full load, full race continuous WOT operation.

I would not open it up now if a rebuild is just over the horizen.

 

you need to use Castrol 20w50 for that Classic vehicle and you may never have to do anything else to it.

http://www.castrol.com/castrol/gener...tentId=7032644

Exceptional Engine Protection for Classic Cars

Finally, a motor oil that's one for the classics...

Today's engines face different demands than those of yesteryear. Now classic car owners who are particular about what they put in their vintage vehicles can receive modern wear protection from a high–zinc formula specially engineered for classic engines.

Back in 1906 Castrol created its first automobile lubricant. Since then, our leading–edge technologies have protected generation after generation of engines. Castrol SYNTEC 20W–50 motor oil is geared to protecting, preserving and helping extend the life of your vehicle from an age gone by that still lives on.

Key Benefits *


Contains increased zinc levels for extra engine wear prevention.
Utilizes proprietary additives and base oils to reduce metal–on–metal contact of aging engine parts.
Engineered to increase wear protection for classic cars with flat tappet camshafts.
* SYNTEC 20W–50 does not meet the catalyst compatibility requirements of vehicles manufactured since 1993.

 

Yeah, 15 PSI at 700 RPM hot is good. My 390 is running 15-40W oil and has 30 PSI hot at idle and that's using a standard oil pump.

OJ

 

Thanks for the replys,
I think that I will try a little heaver oil as mentioned and see how it does.
I never relized what my oil pressure was untill I put a mechanical gauge in this past week. It more than likely has been this way since I have owned the truck and I have put 8500 miles on it.
I am just used to my other truck with a 460 holding steady at 60 cold to 50 hot.

 

Redneck Girl Join Date: Jun 2010
Location: hesperia calif.
Posts: 170


you need to use Castrol 20w50 for that Classic vehicle and you may never have to do anything else to it.

http://www.castrol.com/castrol/gener...tentId=7032644

Exceptional Engine Protection for Classic Cars

Finally, a motor oil that's one for the classics...

Today's engines face different demands than those of yesteryear. Now classic car owners who are particular about what they put in their vintage vehicles can receive modern wear protection from a high–zinc formula specially engineered for classic engines.

Back in 1906 Castrol created its first automobile lubricant. Since then, our leading–edge technologies have protected generation after generation of engines. Castrol SYNTEC 20W–50 motor oil is geared to protecting, preserving and helping extend the life of your vehicle from an age gone by that still lives on.

Key Benefits *


Contains increased zinc levels for extra engine wear prevention.
Utilizes proprietary additives and base oils to reduce metal–on–metal contact of aging engine parts.
Engineered to increase wear protection for classic cars with flat tappet camshafts.
* SYNTEC 20W–50 does not meet the catalyst compatibility requirements of vehicles manufactured since 1993.

Chellie, are you a real person? I've read several of your posts and you come off as an ad agency. Or at least the representitive of one.

 

Your results sound like my engine:

Cold it hits the max of 85 psi (I have the pressure relief spring in the oil pump set for this)

Hot idle at 750 rpm, I get 15 psi, sometimes 13 depending on the filter I am using.

At 2000 rpm I get 55 psi

Higher rpms get me back to 85 psi.

I use a HV oil pump and 0.0025" bearing clearances with 20W50.

I think low oil pressure is mostly based on main bearing clearances, and the Ford factory specs had quite a range for permissible clearances, so I would expect some difference, engine to engine.

That 10 psi per 1000 rpm thing seems to have been derived to fit Chev's where Fords may need a bit more. Basically, the oil flow at the bearings is the concern, and as an FE has longer and smaller diameter oil galleries, it might be expected that the pressure near the filter in a FE might have to be higher than that measured in a Chev in order to get the same oil flow at the bearings.....assuming the same bearing clearances.

So, having loose bearings may mean lower oil pressure, but as the flow of oil is probably fine, there shouldn't be much to worry about. Besides, most oil idiot lights are designed to warn you when the pressure drops to 6 psi, so even at 15 psi, you have a large safety factor if 6 psi is a safety criteria. Of course, the pump has to be sucking air to get as low as 6 psi in a healthy engine....i.e. low oil in the pan and it sloshes around so the pump gets some air once in a while.

 

The cam bearings are an often overlooked area regarding a loss of oil pressure. Many people neglect to replace the cam bearings when doing a backyard rebuild, mainly because they don't have the installation tool. Gouging the cam bearings when replacing the camshaft causes a loss of pressure that can be pretty severe at times just as high mileage and heavy valve springs cause the bearings to wear and lose pressure.

 

Those pressures are not all that bad.

In your case, I would do one thing to try to shore up the idle pressure:

CHECK THE ROCKER ARM TO SHAFT CLEARANCES, or at the very least, pull the rocker shafts and put a restrictor in the oil feed in the head and reinstall and recheck the pressures.

One of the reasons the FE likes to flood the heads with oil is that the rocker arms and/or shafts are worn and they let a large amount of oil out. Try restricting the oil feed and see what happens to those pressures.

Like Mel said about the cam bearings, they can be a problem, but what feeds the rocker shafts? The #2 and #4 cam bearing. Too much clearance between the rocker-shafts and the rocker arms, and the oil pressure will drop off, especially at idle.

 

Thanks agin for the good info,
I have upgraded to a 20w-50 castrol and it helped by almost 10 psi hot not much change cold , I live in texas and the daily temps have been staying around 100 in the shade. Dont know how it will do this winter.
I checked the rocker arms and clearance and I do have a very healthy supply of oil here, so This weekend I will put in a restrictor. I have a preety good feeling this will help alot.
Did not even think about cam bearings and I know the previous owner did redo the top end after bending a pushrod.
This old truck might just out work and live me.

 

Good plan. Hopefully it will be the answer, I don't think it'll hurt.

 

The reason the 20w50 helped the idle and not the upper RPMs is because you are probably already operating at a high enough pressure that the bypass on the pump is opening up and dumping pressure. So the thicker oil didn't help the higher pressures, but it certainly helped the lower RPMs.

We once had a discussion a while back on here, and the old "FE's flood the heads with oil" thing could very well be just a bigger-than-normal clearance between the rockers and the rocker shafts. The "band aid" is to restrict the oil feed in the head to the rockers, and is probably still a good idea to do that when the rockers/shafts are brand-new, because as the rockers/shaft wear, you want the bottom-end pressure to stay up no matter what.

Good luck with it - 25 PSI when hot is GREAT.

That's what my almost brand-new Ford modular V10 got, and still gets when ambient temp is near 100F.

 

Hi, Yes I am a real person LOL ,I have been a truck, diesel and heavy equip mech for over 35 years, i am the only Female Fleet Equipment Mechanic III working for the City of Pasadena, Friday is my last day working, as I will be Retired, Yea, I turn 56 on Wensday, Yea I know i look 29 Bake me a cake LOL As you can see, I am a little salty having been working around male mechanics for most of my life, I should have been BORN a boy LOL I love this stuff, I am a profesional, I used to have my own heavy truck and fork lift repair buisness, back in the early 80s, the recession back then caused me to retire the buisness, I had work, but no one had the money to pay me, I have a high IQ, and a lot of this stuff comes easy to me, I graduated high school, top Industrial arts Student, in automotive, electronics, metal shop and drafting, yes I am THE Nerd and Geek type like most mechanics are Take care and have fun, Chellie

 

Hi Moto Mel a little off topic, but here is another one of my Hobbies I told you i was a GEEK/NERD

Giant Rc Foamie Biplane Scratch Build - WattFlyer RC Electric Flight Forums - Discuss radio control eflight

YouTube - Chellie takes the sticks!

Watch in Full Screen


YouTube - Chellie's scratch-built bipe - maiden takeoff

my friend steve is doing the maiden flight, he is a much better pilot

 

Glad the 20w50 oil help out, it will be fine in the winter months, because it will flow like a 20w oil in the cold, take care and have fun, Chellie