oil pressure fe 390

[MaSnaka]

I have not learned trial by fire that I think most of you guys have. My high performance experience is somewhat novice. I purchased a used Cobra with a rebuilt fe 390, had it in the shop getting some clutch work done and the mechanic said my oil pressure was questionable...at cold idle it would read just over 25 lbs and not move significantly up or down with engine temperature or RPM fluctuations. I checked the guage which seemed ok, replaced the oil pressure sending unit, no change there. So I replaced the oil pump with a high volume pump and now have 50 lbs at cold idle and at 190f engine temp it will gradually drop to 30 lbs as the oil heats up. The pressure doesn't change if I'm idling or at freeway speed when the engine is warm. Should I be concerned or is this adequate. I get different opinions depending on who I ask. Your help and advice please. Thanks!

John
Classic Roadster
Silver no stripes

[elgecko]

Just got done building up my 390 for the Cobra. Haven't fired it up yet but I did prime it with my drill. It was 65-70 lbs with my drill turning about 600 rpm (?). Cold oil.
I'm sure some experts will chime in here soon.
Dave

[flwolfman]

Sure doesn't sound right. My 390 pegs my gauge when cold (over 100 psi) and then comes back down to normal when warmed up. I would like to hear some more on this too.

[tpiini]

While those pressure levels aren't indicitave of a NEW engine, they're certainly high enough that I wouldn't worry. I've seen loose engines running 10 psi at idle without problems.
Tom

[Carnut427]

Originally Posted by tpiini

I've seen loose engines running 10 psi at idle without problems.
Tom

The rule of thumb is 10 psi per 1,000 rpm...as at 4,000 rpm you should have in the neighborhood of 40 psi. The oil pressure should go up in relation to the rpms. I don't know what your problem is, but you'll gain some more by changing the pressure spring in the oil pump to a high pressure spring, available at http://www.precisionoilpumps.com/. You'll have to call him to order anything, his website doesn't list everything he sells. He's excellent to deal with.

[kbisconti]

My 390fe runs around 30 lbs at idle and 60 lbs around 3000rpms. Did you also upgrade the distributor shaft when you changed the oil pump? Good idea. Did the guy that rebuilt the engine add oil restrictors in the heads?

[decooney]

I am running the same as kbisconti. From what I've seen in FEs and some of the ones that break, it seems having a bit higher oil pressure in an FE is good, (not too crazy), however the key to making it all work top to bottom is ensuring you have the correct volume and flow. This is one reason why I had FE Specialties blueprint my oil pump, block, rods/bearing, and heads for proper oiling. When my motor was done, we ran it on a stand working on regulating the oil flow and volume to the rockers / cylinder heads with restrictors as kbisconti mentioned. The other issue that I've seen is people having too much pressure, running higher viscosity oil, and breaking distributor parts with cold starts or not letting it warm up properly before driving. So, one might conclude there is a happy medium range to consider for oil pressure and oil viscosity for FEs. i.e this aint no Chevy engine, and if you listen to a pure Chevy engine enthusiast on FE oiling, watch out!

[grumpy]

MaSnaka,
As DECOONEY noted, these are old tractor engines, however they do perform, and have almost the perfect range for a street 2400 lb or so COBRA. Do not compare to a high oil pressure or pressurized cooling system as needed in a Chevy engine.
Optium pressure at idle is around 40 lbs plus a little, warmed up, however 20 lbs and up is fine as long as the 3000rpm range and up gets it into the proper lbs for the wear/miles you have since rebuild, about 50-80 lbs. We never use "spring kits" just to boost pressure to give comfy feelings on pressure in the FE. More depends on the oil type, oil pump, filter, and and other oiling system modifications that some performance engine builders do.
grumpy

[MaSnaka]

Thanks for the input guys. I would feel better having more oil pressure. Sounds like I need it. Since I wasn't around during the rebuild (wasn't my car then) I don't have a tight grip on all the details on the build. I am running valvoline 20-50, I do have a remote oil filter and cooling system, I have about 6000 miles on the engine since it was rebuilt. I did replace the oil pump with an off the shelf unit at PAW. It is listed as high volume, not high pressure. Should I go with high pressure? I might as well get a windage tray while I'm under there. I used the existing hex shaft from the distributer. Is there a reason why I should change that? I know dumb questions are better than dumb mistakes so please bare with me here. Your help is appreciated.

Thanks,
John

Classic Roadster
Silver no stripes

[kbisconti]

You may want to call a FE engine builder such as FE Specialties or Southern Automotive, or Kieth Craft and ask more about how important the heaver distributor shat is. You can also look at Summitracing on line and read about oil pumps and Oil distributor shafts.
This is from Summit Racing: Good insurance at a low cost.
These oil pump driveshafts are CNC-machined from 4130 chromemoly and centerless ground to avoid stress risers. These race-proven shafts eclipse breakage-prone stock units that frequently fail when used with high volume oil systems, heavy racing oil, or high rpm applications. The ends are induction heat-treated to reduce wear.

[Carnut427]

Originally Posted by grumpy

...We never use "spring kits" just to boost pressure to give comfy feelings on pressure in the FE...

Side oilers came with high pressure pumps from the factory, running up to 125 psi cold. The spring available from Performance Oil Pumps brings the high volume oil pump up to this limit. IMO, all FEs can use this insurance because of the large rod bearing size. Chevies don't need or use high pressure pumps, but FEs do if they're going to live at high RPM.

[grumpy]

Carnut427,
I understand the SO427 FE came with a HV FORD NASCAR pump, but very very few 390's did, unless you are including the RACING 390's such as the 401HP etc. Hopefully they are in their original cars and properly restored.
Have never seen a stock Chevy with a High vol/press pump from the factory unless it was a "crate engine", engine in white for NASCAR machining, or one of the Chevy Racing applications, one very similar to the street engines in any of the 60's manufacturer's.
MaSnaka,
The base 390 and the base oil pump should be fine, I would not pressure up with the spring method, UNLESS you are upgrading the seals, gaskets, chamfering the crank, block ports, rodding out passages, etc. Doing just that you are not changing the volume of oil to the crank to barely over 10% of stock with "just spring" method, but however, will fill the lifter gallery with the difference. By "orficing" the oil passages, you can push more oil to the crank if the engine is going in the the 5000 rpm plus region a lot. With that you need a FE person to do the machining and fit up, not "just a engine re-builder".
Good Luck
grumpy

[Carnut427]

Grumpy,
We agree that chevies didn't use high pressure pumps, although most high performance engines of any brand wisely come with high volume pumps.
In this forum, most people running 390s are building or having them built for high performance, and the consequential higher rpms. If one is building a stock ‘merely transportation’ motor, a stock pump will indeed be fine. However, I question the idea that the high pressure pump was good for the 427, but is it bad for the 390. The bearing sizes are the same, and if the 390 is being used for performance, so are the forces on those bearings.
I’m not one to argue; therefore, perhaps we can agree to disagree, but I stand by my suggestion, as you may stand by yours, and let the engine owner/builder make what is ultimately his decision, based on the ideas and reasoning behind them.

[Sal Gerace]

I was preoiling my 427 by removing the distributor and using one of Morosos oil pump primer shafts with my 3/8ths drill. I was real suprised at how this really taxed that little drill to turn the pump and oil the engine! I first tried using my 14v cordless drill but the motor on the cordless started to smoke! Should I be concerned with the amount of power it took to turn the pump or ids this normal?

[elgecko]

I believe that the 427 is a little more powerful than that 14 volt drill .
I was using a 18volt drill and it sure smelled funny after spinning that pump for awhile. I was getting 70 lbs. Has a Melling HV pump.
Dave

[Carnut427]

I use a 3/8" standard drill, and even it gets taxed. If these drills are huffing and puffing at turning the oil pump, imagine what forces are working on the oil pump drive shaft. This alone should be enough of a selling point to use a 'heavy duty' or 'performance' shaft.

[MaSnaka]

It sounds like I have come to the fountain of information. What I do with it all is the difficult part. Seems without a complete tear down of the engine I will never know exactly how the engine was set up. Buying someone elses project has some serious risks. The risks of not doing it or having it done yourself means I will always have to wonder. Driving the car today, at 70 -80 mph, 3500 rpm's, water temp 190, oil temp 230, oil pressure is at 25-30 lbs. I do love the exceleration (hitting 5000 rpm) when passing cars or getting on the fwy or just having some fun, but I'm not racing track or keeping it cranked up there very long. I'm not looking to tear down the engine but I am interested in a simple fix if that is possible. Changing out an oil pump and shaft is not a problem. I certainly don't want to creat more problems by putting in too much oil pressure. I still don't know what to do.
HHHHHHHHHHHHHEEEEEEEEEELLLLLLLLLLLLLPPPPPPPPPPPPPP PP...Thanks

John
Classic Roadster
Silver no stripes

[tpiini]

You know,

If it were me, I'd set aside an afternoon and yank the intake off to see if the galley plugs are in place at the rear of the lifter valley. It's not an uncommon mistake to leave them out in an FE build. I think your pressure would be lower yet if they WERE left out, but it would give me peace of mind to take a look.

[Jerry Clayton]

Excessive bearing clearance

Jerry

[BigAl]

I'm with Jerry, Excessive bearing clearance. Oil pumps never seem to fix low oil pressure problems. I used to have a 71 F100 with a 390. It had 3.73 gears
and a hot cam. I loved revving it out but it had almost no oil pressure (2 PSI maybe) when hot at idle. The factory oil light would flicker at stop lights. I drove the heck out of it for two years with no problem before I replaced the crank and rod bearings.

I would just keep driving your car and not worry about it. If this makes you feel any better check out Chevrolet's minimum oil pressure specs. for new truck.

1000 RPM-6PSI min.
2000 RPM-18PSI min.
4000 RPM-24PSI min.