Oil pressure questions and concerns.

[NUTNDUN]

Hey gang,
I apologize for the long post but I think it will be best to be able to give the best description I can. I can't remember if I had posted about it or not before but I had a dilema with my 398 windsor where I broke 4 valve springs and seized the roller on a lifter. Without going in to too much detail on the motor before the valve springs broke I was having random 5 - 10 psi drops in oil pressure which I think we have come to the conclusion that I didn't have enough oil in the pan.

Anyway I put a new m83hv oil pump in it, it is a canton rear sump oil pan. The valve covers are fabricated aluminum to clear the roller rockers and valve stud girdles. They don't have any baffles in them. I have a header/crankcase evac system on it. As it stands I have 8 qts in the pan plus 1 qt for the oil filter. I don't have the random drops in oil psi anymore. The problem I am having now is what seems to be oil not returning to the pan fast enough at higher rpms. I have the rev limiter set at 7,000 rpm and it would do more but I want to keep it together. A good example is when I am in 2nd gear and mash on it and it gets somewhere around 5,000 - 6,000 rpm the oil pressure drops 5 psi.

Here are my oil pressure readings:
at idle cold: 62 psi
at idle warm in gear: 30 psi
at idle warm out of gear: 40 psi
cruising warm: 50 - 52 psi

The heads have screens that are jb welded in place at the oil return holes. They were put there by the previous owner, the whole motor was a drag motor for a fox body mustang. I am running valvoline 10-30. I was going to pull the screens out when I had the motor apart but didn't for some reason. I also think part of my problem may be the header evac system is sucking oil out of the valve covers. I need to pull the hoses off the headers to double check. It tends to let out a puff of white smoke when it is started after being shut down for a couple of minutes and when it was apart the cylinder walls looked excellent and the pistons were clean. I am at wits end with the oil pressure issues. I can probably pull the screens out and knock the jb weld out while the heads are on, just have to make sure I get most of the mess and then run oil down the drain holes to clean it out then change the oil. I don't know if it may need restrictors and if it does I have no idea where they go. The motor runs awesome and is a beast, I just want to make sure everything is right before I go taking it down the track.

[george worley]

Sounds to me like a oil pick up problem,or it could be that the oil is staying up in the heads/valve cover area and not returning to the pan quick enough.

[NUTNDUN]

I think I am going to take the header evac setup off the truck for now and only use it when it goes to the drag strip. My buddy that has a performance shop and who is the one that set the heads up with the new springs and retainers said the evac is what is sucking the oil out. It could also be part of the reason not enough oil is returning. He thinks I don't have enough oil in it yet. There is a possibility that it is a 9 qt pan and that means I am still a quart shy.

[NUTNDUN]

I figured I would post a couple of pictures of the motor:

[BobbyFord]

Are the oil pan and oil pump pick-up tube matched?

[NUTNDUN]

Ya they are matched and it has 3/8" clearance.

[DuckRyder]

I don't see the screens as being restrictive enough to cause this.

Definately make sure the pan has the designed capacity in it.

I agree with removing the header evacuation system.

[NUTNDUN]

I am going to pull the header evac off tonight. I need to get new spark plug wires, the one tab broke off the number 2 wire and the wires were new. I don't know what the design capacity is on the oil pan. It was with the motor when I bought it and it was painted black but where the paint is chipping away you can see the gold zinc plating and the design of it is pretty much identical to one of cantons pans. We had added another quart of oil to it after it dropped like it did but I haven't had a chance to really test it yet. As it sits right now there is 8 quarts in the pan and one in the filter. Maybe with the evac setup not on there it will help with letting the oil return faster since it won't be sucking any oil itself. The inside of the evac cannisters were soaked with oil so I know it is pulling oil in. The valve covers aren't baffled because of there not being enough room. The rubber grommet on the one side is baffled but that is the one that looked like it was getting more oil then the other one. I will get some breathers to put on to replace the evac setup. Hopefully by the end of the week I will have everything and can test it out and will let yas know what I find.

[averagef250]

Are you running a good windage tray/crank scraper?

If you aren't, no matter how much oil you put in the pan it's going to end up everywhere but in the pan at high RPM. HV oil pumps have many extra considerations that are often overlooked. Running 10W30 may also be an issue. Good shops don't usually build an older engine to run 7K+ and keep bearing clearance for light oil. I've always run high quality 20W50 or 15W40 in my race engines and used the appropriate oil clearance to match. With the heavier oils it takes a little more consideration for cold starting, don't tach her up until she warms up a bit, but hot the heavier weight oil has more protection with larger bearing clearance.

I hope you get this figured out.

[NUTNDUN]

Are you running a good windage tray/crank scraper?

If you aren't, no matter how much oil you put in the pan it's going to end up everywhere but in the pan at high RPM. HV oil pumps have many extra considerations that are often overlooked. Running 10W30 may also be an issue. Good shops don't usually build an older engine to run 7K+ and keep bearing clearance for light oil. I've always run high quality 20W50 or 15W40 in my race engines and used the appropriate oil clearance to match. With the heavier oils it takes a little more consideration for cold starting, don't tach her up until she warms up a bit, but hot the heavier weight oil has more protection with larger bearing clearance.

I hope you get this figured out.

There is a crank scraper in the pan, I don't know how much it does though with it having the main girdle. I know the clearances are on the looser side because of it being built for a race motor. That was one of the questions I did want to ask about the heavier oils and you just answered it for me. I am going to change the oil to 15-40 now that the motor is basically broken in for the second time LOL. I also found out that I was using the wrong spark plugs. I was using autolite 24's and they only have like a 3/8 - 1/2" reach and the ones I am supposed to be running are the 3924's with 3/4" reach. The 24's also have an angled seat and the 3924's have the sealing washer. I am anxious to see how much of an improvement that makes. I am going to go get breathers to replace the header evac, new spark plugs, and I will also get some new oil and see how she does. This is the only bad thing about buying someone elses combo and not having all of the details. The previous owner built the motor for the following season and then ended up selling the car and the motor sat together for approx 3 years assembled which is what we think caused the demise of the valve springs. The car ran 8.60's in the 1/4 with a 250 shot with the previous motor and this one was supposed to do as good or a little better. I bought a new oil pan and pick up for it but it wouldn't clear the girdle so I put the original pan and pickup back on it.

With 2.75 rear gears and a c6 from a rolling first gear at any speed it will blow both the tires and you hit second and it will keep blowing em off till you run out of room or let out of it. I think it is hilarious having an open diff that blows posi. That is all changing this weekend, we have a set of 3.50's going on a full spool so it should be a lot better. I just hope I can get the oiling issues worked out.

[NUTNDUN]

I went and got the breathers to replace the header evac. I also got a case of valvoline vr1 20-50 racing oil and a new filter. I made up my mind last night to pull the screens out of the drain holes.

I discovered a couple things:
1) JB weld is magnetic / never knew this and a friend and I just had that discussion this past weekend LOL.
2) I think the screens are part of the problem, they are pretty thick. They are probably close to .040 thick and were shoved in there to make the shape of a thimble. So it was taking up around .080 of the drain hole not to mention the jb weld that might have been affecting the flow also.
3) The other problem that I may have is I took the front screens out first and then I got the flash light out to look in to the drain hole and the oil hole doesn't match up with the block. It is about an 1/8" off to one side. I didn't notice it because of the screens. Both of the front drain holes are like this. I got the passenger side rear screen out and it is back far enough that I can't see in the hole right but I used a long skinny screwdriver to see if I could feel a lip and if there is one it isn't much. I want to do some more checking today after work, if the rear ones are offset close to what the front ones are then the heads are coming back off and I will clean it all up.

I will also try and get some pictures of the screens so it makes it easier to describe how much room they were taking up.

[flyboy71]

Is it possible the high volume pump can be pulling oil out of the sump too much at high RPM to where its running out? Especially if youre running 10W30. You mentioned a lot of oil in the evac, Im wondering if youll have oil blowing out the breather if all of it is being pumped up there. Im no expert, just curious.

[NUTNDUN]

It is definitely pumping the sump dry at high rpm. I think it is a combination of things and hopefully will be sorted out today when I get home. I think switching to the thicker weight oil to make the pump work a little harder will help especially with the looser clearances on the bearings. Taking the screens out of the drain holes in the heads is bound to help. There is also the possibility that maybe it should be at 9 quarts in the pan instead of 8. I will be able to rest a little easier once I know for sure the oil return holes at the back of the heads line up a little better.

I am thinking about taking the 20-50 back and getting 15-40. I am afraid the 20-50 might be too thick. I remember what it was like pouring 20-50 diesel oil into my big truck especially when it was winter time, stuff would pour out like molasses.

[averagef250]

You really need to know what bearing clearance the engine has. The Ford, chevy and AMC motors I've run in the 7-8K area have all run on 20W50 and had a thou over max oil clearance intentionally. I've honestly never had a bottom end issue that wasn't piston related. I'm religious about warming up an engine before I run it, usually 30 seconds, but with a race type engine on cold fire up I'll run it 1500-2500 until the oil temperature starts to come up. With 10K street/strip mile teardowns, none have ever had any measureable main wear and one had pre-detonation marks on the rods, but no wear otherwise.

If you have stock bearing clearance in the bottom end you shouldn't play with thicker oils and you really shouldn't be spinning it over 7. Also, if you have extra clearance and you're running 10W30 you're setting the engine up for major failure.

[NUTNDUN]

That is the one thing I regret doing when the motor was apart this last time is measuring the clearances. It was all brand new and I never gave it a thought. I put SAE 50 racing oil in it tonight. I thought for sure the oil pressure would have been higher on cold startup but it was at 64 psi at startup. I let it warm up for a couple minutes and then cruising it never dropped below 60 psi and then at an idle it drops to 50 psi in gear.