Argess,
When I built the engine I checked every clearance in it. The mains were about .0025 and the rods were about the same too. That's the best of my recollection. I don't run restricters in the heads either. The oil galley from the pump is drilled out bigger. The hole going into the HV oil pump is gasket matched and the three ( best of my recollection ) oil holes in the mains were tapered out so the oil would flow into the bearing hole would be better. The crank I have is a 406 that has the groove in the mains for more oiling. I would think if anything was built for low oil pressure this would be it. I listed the oil pressure before as 20 lbs at 500 rpm, it's actually 25. When you start the engine cold I'm thinking it goes to about 75-80 lbs. The 2000 rpm 60 lbs was correct so was the 45 lbs at 1200 rpm. This is when the engine reaches 190 degrees and I'm using 10W-30 Valvoline. I broke the cam in on 5W-20 cheap mineral oil from Walmart. I just used it for the first hour of running. At 8 quarts it still isn't cheap but I didn't want to leave it in for a long period of time.
I actually thought I had a problem with it idling on 25 lbs oil pressure, my Silverado says 45 lbs when idling and it's got 76 thousand miles on it. The 390's I have also read low at idle come to think of it. But, I heard you only need 10 lbs per 1000 rpm. Jim

 

Argess,
I am also using new adjustable rockers from Pop's, he makes them down in Ky. He also supplied the push rods.
If I can't jack the car up easily I may go to his shorty headers also. My Maddog full length headers drag the ground every time I hit a bump with the old engine in it. I may have to lift the car anyway if the oil pan sticks down too low. Jim

 

Thanks for the info. I've done the same oiling mods as you.....pump to oil adapter enlargement, tapered some of the main bearing saddle oil holes to match the bearing holes, and I used the oil filter adapter with the larger cavities. I also tapped for screw-in plugs for the oil galleries vs those pressed in ones. I didn't drill out the rear obstruction in the main oil gallery I've heard about, as I could never find one.

My oil temperature may have something to do with the change. At light highway cruising, water temp is at 180 and oil temp is 200. In city traffic on a hot day, water temp comes up to 190 and oil temp gets close to 220F. If my oil is getting hotter than yours (and hence...thinner), it may be because I don't use a vacuum distributor so I'm always driving with late timing designed for power which generates extra heat. However the fact you are getting such good pressure with only 10W30 when I'm using 20W50 still indicates I have something quite different going on than you do.

That old adage about 10 psi for every 10 thou of rpms seems to have originated with Chevy small blocks which I understand have much larger diameter oil galleries. I sort of think that bearings, regardless of the engine type, need the same flow of oil. With the Ford smaller galleries, more pressure is needed back by the filter to ensure the same flow at the bearings as a SBC.

I still have one of my older blocks around....water jacket cracked, but useful for a boat mooring. Think I"ll check it and see if I left any plugs out. I kind of think I did leave out a front end lifter gallery plug, but didn't see it mattered as the lifter galleries are blocked off. Something in the back of my mind says to look at the dist hole. It gets its oil feed, but I seem to remember another gallery drilled crossways. Maybe I'm losing a bit of oil there.

Seems to me Ford says between 45 and 60 psi at 2000 rpm.

On a more positive note. For many years, I've seen people post concerns about their oil pressure (in various FE forums), yet it's normally very close to mine. Interesting. Thanks again for giving me the details.

Edit: I doubt this is a problem for me, but I didn't know about it and will check it out:

http://www.erareplicas.com/427man/engine/oilpress.htm

 

Argess,
I lied to you or my eyes don't work as well as they used to. I just come from the hanger where I ran my engine again for 30 minutes. I wrote down all the pressures just to reasure myself I wasn't lying to you.
My engine is set on 10 degrees initial timing if that were to make a difference. This is with Valvoline 10W-30 motor oil.
Starting it cold with fast idle set and doing 1300 rpm I have 75 lbs oil pressure and 19 inches manifold pressure.
Letting it warm up to 190 degrees and having it idle at 600 rpm I had 19 lbs oil pressure and 14 inches manifold pressure.
At 1200 rpm I had 40 lbs of oil pressure and 19 inches manifold pressure.
At 2000 rpm I had 60 lbs oil pressure and 21 inches of manifold pressure.
I was sure I'd seen higher oil pressure at idle but I sure as _ _ _ didn't today. Hope this helps. Jim

 

No problem, and I appreciate your honesty. I suspect if you get it really good and hot, your pressure measurements will be closer to mine.

Actually your eninge is fairly close to mine in mods, etc. Feel free to PM me if you like and I can let you know what did and didn't work for me.

 

Guys,
I took some pictures of the engine starting, 600rpm and 1400rpm to show oil pressure and manifold pressure. After a few more hrs I'll take the 10W-30 out and put in a little heavier oil. I'm pleased with the way the motor runs. Jim

 

Darned good oil pressure as far as I am concerned. By the way, why the spacers on your manifold bolts?

Back to oil pressure. I did some very rough math on my engine. It doesn't allow for a lot of things, such as the order various parts receive oil, but it seems to make some indication about what's happening.

I worked out the area the oil has to escape, and assumed it's proportional to flow (which could be wrong). For bearings, I multiplied by 2 as it leaks from both sides, and then multiplied by the number of bearings of that type in the engine. I ignored the dist lube gallery. For the head restrictions, I just multiplied by 2 as there are two restrictors. Here's what I cam up with for oil losses based on escape area:

Rod bearings 45% of oil flow
(based on 0.0025" clearances and always oiled due to fully grooved main bearings)

Main bearings 32% of oil flow
(based on 0.0025" clearances)

Cam bearings 19% of oil flow
(based on avg cam journal diameter and avg stock clearance of 0.002")

Heads (each with 0.090 restrictors) 4% of oil flow

Now I would guess the dynamics of a rotating assembly can change the math. And a restrictor isn't quite the same as bearing leakage. And maybe volume flow is not proportional to surface area....I admit to this being a really rough mathmatical excercise because I'm not that smart....LOL. However, it sure looks like the rods lose most of the pressure.

Maybe this shows why some builders use 0.0025" on the mains, but reduce the rods to 0.002"?

I sort of think that if the rods are the #1 cause of low pressure at a hot idle, it's hardly a worry as they must be getting oil for it to leak out, so the flow is there. And of course, the rod bearings are the last stop for oil before it gets to the pan (excuding the heads).

I think I need to replace the batteries in my calculator now.....

 

Argess,
The original 406's suppose to have came out with them. I'm like you, what's that for.
I can't imagine sitting down and figuring each component oil pressure loss. I'll take your word for it.
I'm sending a picture of my engine stand. It's been a blessing as far as putting engines together and adjusting on them. When they go into the car the jobs done. No drips, no errors, no adjusting carbs over the fenders, it's more plug and play this way. Jim