# HOW MUCH OIL DOES A FACTORY HEAD HOLD?



## PontiacJim (Dec 29, 2012)

*HOW MUCH OIL DOES A FACTORY HEAD HOLD?*

I my quest for facts and what the oil fill level is based on quarts in the oil pan, I wondered how much oil is held up in a Pontiac head before it begins to drain through the oil drain holes. I have read think they know, but where are the facts?

I first measured the block deck angle on my 455CI engine block to determine that needed angle of the head to do my test. I came up with a 45 (maybe 45.5) degree angle for the deck angle. So I had to set my head up at a 45 degree angle for my test.

Pic # 01 - I used a 1968 #15 head I had. Cleaned it up of any heavy sludge to get my best readings.

Pic # 02 - 05 are looking down the 4 oil drain holes starting from left to right. You can see a scallop in the head that channels the drain oil out through the head and into the lifter valley.


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## PontiacJim (Dec 29, 2012)

PontiacJim said:


> *HOW MUCH OIL DOES A FACTORY HEAD HOLD?*
> 
> I my quest for facts and what the oil fill level is based on quarts in the oil pan, I wondered how much oil is held up in a Pontiac head before it begins to drain through the oil drain holes. I have read think they know, but where are the facts?
> 
> ...


Pic #06 - 08 is a look into the drain holes through the intake side surface. What I want you to see is how jagged & rough the casting is - not smooth at all. In the quest to get return oil back into the pan as quick as possible, I think it might be a good idea to go into these pockets and grind/smooth the return passages that dump into the lifter valley. Pic #08 is a good shot showing 2 of the oil drain and how rough they are.

Pic #09 - I first plugged up the head bolt holes so no oil would drain out of them if the oil level got high. You will see this in later pics. I purchased a valve cover gasket and used an old Edelbrock valve cover with the breather hole in the top. I bolted it down just as factory. I did not know what to expect or how high the oil level might actually go inside the head area.


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## PontiacJim (Dec 29, 2012)

PontiacJim said:


> Pic #06 - 08 is a look into the drain holes through the intake side surface. What I want you to see is how jagged & rough the casting is - not smooth at all. In the quest to get return oil back into the pan as quick as possible, I think it might be a good idea to go into these pockets and grind/smooth the return passages that dump into the lifter valley. Pic #08 is a good shot showing 2 of the oil drain and how rough they are.
> 
> Pic #09 - I first plugged up the head bolt holes so no oil would drain out of them if the oil level got high. You will see this in later pics. I purchased a valve cover gasket and used an old Edelbrock valve cover with the breather hole in the top. I bolted it down just as factory. I did not know what to expect or how high the oil level might actually go inside the head area.
> 
> ...



Pic #10 - I use these stands I picked up at Harbor Freight to do head work. I drilled holes through them at the tops and then use a 9/16" bolt to attach to the head. I used a level table I have to set up this test. Then I used the magnetic angle finder (Home Depot) and set the angle of the head to match the block angle just as it would be when installed on the engine. Got it set at 45 degree and then tightened my stand bolts and double checked the angle again.

Pic #11 - Ready to fill the head with my dyed water. I filled my water container to the 1 Cup level to start and thought I would have to add from there. But, I was surprised when it did not take much of a pour to see water draining out the oil drain hole. I poured real slow as I did not know what to expect. When the water began to drip out, I stopped. Hmmm, still quite a bit left in my measuring container.
So in an effort to figure out how much water had filled the head before coming out the oil drain hole, I used my CC graduated syringe and added water to fill the container back up to its original fill of 1 Cup. The amount? 40 CC's.
So how much oil remains up in the head BEFORE additional oil drains out of the oil hole? 40 CC's per head or 80 CC's total, which is 2 3/4 ounces total. That is the equivalent of just ove 1/3 of a Cup (8 ounces). 1 Quart is 32 ounces. 2 3/4 ounces of a 32 ounce quart of oil is not much.

Pic #12-14 - To see exactly what the water level was inside the head, I removed the valve cover without disturbing the head. Here you can see how the water level sets in pic #12-13. Pic #14 shows how the head area at the head bolt is smooth and has a slight pitch so no water builds up. This is not true of the other head bolts.

Pic #15 is the cast pocket that the outer head bolts go through. Although no water went into or filled these pockets before the water went out the oil drain holes, these pockets will/do collect oil. How much? The left pocket took 12 CC's before spilling over into the water in the head. The pocket on the right too 13 CC's to spill over. The head bolt nearest the right head bolt has a ridge that acts as a dam, but can also trap a little oil within it. It took 2 CC's to cause it to spill over.

These numbers are not too important as if/when these pockets fill, they won't drain away as the oil pumping through the heads (via the pushrods/rockers) will, so their volume is basically static. The same goes with the oil found throughout the engine as I looked more closely at it. The oil in the passages will most likely remain once the engine is fired up and oil is pumped through the engine.


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## PontiacJim (Dec 29, 2012)

PontiacJim said:


> Pic #10 - I use these stands I picked up at Harbor Freight to do head work. I drilled holes through them at the tops and then use a 9/16" bolt to attach to the head. I used a level table I have to set up this test. Then I used the magnetic angle finder (Home Depot) and set the angle of the head to match the block angle just as it would be when installed on the engine. Got it set at 45 degree and then tightened my stand bolts and double checked the angle again.
> 
> Pic #11 - Ready to fill the head with my dyed water. I filled my water container to the 1 Cup level to start and thought I would have to add from there. But, I was surprised when it did not take much of a pour to see water draining out the oil drain hole. I poured real slow as I did not know what to expect. When the water began to drip out, I stopped. Hmmm, still quite a bit left in my measuring container.
> So in an effort to figure out how much water had filled the head before coming out the oil drain hole, I used my CC graduated syringe and added water to fill the container back up to its original fill of 1 Cup. The amount? 40 CC's.
> ...



What was learned? The amount of oil that is left up in the heads, almost 3 ounces, is very small when considering that Pontiac uses 5 quarts in the pan and 1 in the filter. Should this be a concern? Not really. Could you add a little extra oil? Sure, check your dipstick following your oil change and run the engine for a few minutes, then check it again and add oil if needed to bring the fill level to the full mark. You don't want to over fill as the oil level is already very close to the crank throws and too much oil could cause aeration of the oil by the whipping action of the crankshaft. If you like to race or run your car hard, then it would only make sense to use an oil pan with at a minimum an oil baffle and keep your oil up closer to the fill mark than not.

Understand that this does not relate to the amount of oil that circulates through the engine at the various RPM's. Many factors come into play with regards to how much oil an engine uses while running and how much is left in the oil pan - this is another question all together and should not be confused with this write up. The amount of oil left in the oil pan at various RPM's would need to be determined by the oil pumps oil pressure, how many gallons per minute the oil pump flows, the use of oil restrictors, bearing & other clearances (whether the engine is worn, new, or set-up for race), and type of oil filtration set-up. So determining how much oil an engine actually needs & uses is not a 1 size fits all and many variables come into play. This is where a good engine builder and experience can help.


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## 1968gto421 (Mar 28, 2014)

Whoa, creative and well done JIm


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## BearGFR (Aug 25, 2008)

Nice. You've got me thinking about testing my Edelbrocks. I've heard from multiple sources that their oil drain back isn't as good as stock, but I've not tried to measure it. Now would be a good time, since it's all apart now waiting for a set of pistons to show up.

Bear


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## PontiacJim (Dec 29, 2012)

BearGFR said:


> Nice. You've got me thinking about testing my Edelbrocks. I've heard from multiple sources that their oil drain back isn't as good as stock, but I've not tried to measure it. Now would be a good time, since it's all apart now waiting for a set of pistons to show up.
> 
> Bear


I have read that depending on when the head was actually produced, the later heads got additional oil drain holes. It may not have been a problem on a street engine, but those guys building race engines with the 80 PSI oil pumps and larger clearances may have had more of the issue with oil return.

I have not seen a side by side comparison that shows the differences, so I don't know what the actual change is or if you could modify/add any extra oil drain holes.

For the average guy using iron heads, I don't see any real issue of concern with there being a bunch of oil kept up in the heads (which my testing shows is not very much at all) and most who build big HP/TQ and/or stroker engines typically go with aluminum heads anyway. I don't know how the aluminum heads oil drain back hole location/size compares or matches up with the factory iron heads. As pointed out, the problem, if any, would be pumping more oil up to the top end than can be returned back to the oil pan sump. In this instance, it would be my opinion that that is when you want the larger capacity oil pan (or overfill the stock pan) to ensure you still have enough oil to draw from if the return oil could not quite meet the demand of the oil pump needs - ie where the stock pan could get pumped dry or oil pick-up become exposed and suck air, while a 7-9 quart pan would still have enough oil to keep the oil pump from starving.

I did learn that I think I may take a closer look at my 7K3 heads I have all done up and see if I may need to disassemble them and clean up and smooth the oil return holes. I did the lifter valley area of my block and got it smoothed out removing all the casting flash and jagged edges which can't hurt the oil return flow. Touching up the heads oil returns might not be a bad thing.


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## Old Man Taylor (May 9, 2011)

The E-heads have a much more restrictive oil return back to the pan. I added an extra drain to try to help this situation. I don't have a picture of the drains in the heads, but I've attached a picture of the drain line I added to my engine.


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## Machinest-guy (Jul 19, 2019)

I would hope to add some observations to your thread. There is no doubt oil is distributed throughout an engine in different quantities and in different states of usefulness over time. I feel the static state distribution is interesting but not that important insofar as performance goes because oil distribution in operation is orders of magnitude different. I was able to observe a bit of testing Chrysler did in their valve train development when using clear window valve covers. I've also seen Spintron video of upper end oil flow in Ford and GM V8 development. I believe operational estimates of oil retained in the valve covers at 4000 RPM and up was about a quart in each. The timing cover was full at about a half quart. While their V8 engine valleys are substantially different than Pontiac, I recall about two quarts was held in the closed valley designs before exiting at the front or back of the block. In Pontiac's open lifter galley that oil drops onto the cam and is wrapped around the crankshaft for some period of time before it can drop to the oil sump and become useful again. 
Oil system return path design is perhaps more important than wringing the last bit of pressure side performance out of a pump and pickup because the return side is gravity free flow driven - very limited pressure or none at all available. 

Something which many are not aware of happens in Pontiac (and some other) cylinder heads. The oil return path increases in size as the amount of oil to return to the sump increases. If you look at the rough casting openings they are effectively staged at different heights. When the casting flash is removed it often is like removing a dam. Oil can exit the head at lower RPM and lower standing heights. But there is a question to be asked: Does letting that oil go off the valve spring bases, or never get to wash over the springs, create a beneficial condition or not ? How high should the oil level in a cylinder head be ? 

I would offer up a suggestion that a running oil level in most domestic cylinder heads should ideally be about the height of the valve cover sealing rail or just a bit below the top of a valve guide seal. The more you can cool the springs the longer they will retain tension. This will extend life of valves, guides, and thereby the seats. When more oil can circulate on the top of a cylinder head promoting more equal temperature distribution, fewer cracks will develop over time. 
I notice in photograph #8 an oil return line set into a head below the rail which has an extender raising the cover rail. Maybe moving that line up a bit into the extender area would be beneficial ??. The lower end of that drain seems about right but some checking may be indicated. I know positive crankcase pressure can blow liquid oil back up those sorts of hoses and cause flooding of the valve cover area when at high speed if the lower opening is set below the highest expected oil level in the engine (remember to consider G loads). 
I think mentioning not all oil inside an engine is in the "liquid state" flowing in nice channels back to the oil pan is important. Much of it is droplets bouncing and flying around. Some estimates I've seen suggest as much as two quarts are flying around in the crankcase, wrapped around the crankshaft, flying off valve train parts, and captured by the timing chain at 4000 or more RPM. When this estimate is added to observed amounts of a quart in each valve cover, half a quart in the timing chain area, and two quarts in an engine valley area it is clear only 1/2 to 1 quart is available for the oil pick up to gather when running a 5 or 6 quart system. Adding an extra quart makes sense because much of that extra quart will find it's way back to the oil pump pickup area and prevent sucking air into the pump. 
Over the years many treatments to the inside of engine blocks and heads has been done. For some years polishing the interior of a block and heads to promote rapid oil flow, then perhaps coating the surface with Glyptol or red lead primer was done. I believe since the 1960's and 1970's when this was popular two considerations now lead away from that practice. Polishing those surfaces reduces their surface area by a large factor - almost by half in some cases - which reduces thermal radiation area. Less heat will go into the oil and more will be retained in the block or heads which must be removed in other ways. And Glyptol is a very effective thermal insulator which can make thermal load retention even greater. Ideally one would fin the insides of an engine and run lots and lots of liquid oil over the fins to remove heat. 
Perhaps these suggestions will help someone create a cool running and longer lasting Pontiac. Best regards, Ladd


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## AlaGreyGoat (Jul 6, 2006)

It seems all this is for a engine sitting still. When the car is accelerating with g forces holding the oil at the rear of the engine, how well does the oil
return through the rear holes, only?

Larry


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## PontiacJim (Dec 29, 2012)

AlaGreyGoat said:


> It seems all this is for a engine sitting still. When the car is accelerating with g forces holding the oil at the rear of the engine, how well does the oil
> return through the rear holes, only?
> 
> Larry


Yes, the amount of oil is indeed the amount when sitting still - it is how much they hold. Determining how much oil stays up top, in the engine, in suspension, would probably take a lifetime to put any number on it, and then that would only be for "that" engine.


Think of all the variables - design of the engine and/or specific parts, size of the engine,cast iron or aluminum, oil pan design and depth, oil pan windage devices, oil pump pick-up desgn, oil pump type -wet/dry, smooth return oil surfaces or jagged casting edges, oil weight & type, oil temps, oil pump pressure/volume, size of the pushrod holes/rocker arm spit holes, lifters - hydraulic/solid/roller, oil galley diameter and/or restrictions, bearing clearances, inclination of the engine (factory incline or a good wheelie), G-forces, RPM's, crank surfaces - stock, knife edged, coatings, connecting rod surface areas, internal engine pressures, engine venting, outside temperatures & humidity, and others.

So if you took just 1 specific engine, let's say a Pontiac 400, and did your first round of testing using many of the variables above and got your numbers, then you changed just 1 variable, you would then have to go back and do each of the tests all over again to see how that 1 variable has affected all your other measurements. Then once you got all that data, and you changed just 1 more variable, you would now have to run all your tests again to get correct data, and so on and so on and by the time you collected all your data based on individual changes, you would be retired and the engine would be obsolete. 

That said, anyone who claims how much oil remains in an engine while at rest or running had better have personal experience and the *factual data* in hand documented on some form of media that all can see and reference outlining the engine and its components, what equipment was used to test it, how it was tested, and the conditions under which it was tested. All too often arm chair theorists who think they know, or have a buddy who said, or knew a guy who used to work for...... proves nothing other than they want to participate in the conversation or toot their own horn to impress. Show me the facts.

I think it is pointless to observe oil flow, oil return, atomized oil droplets, in what part of the engine specific amounts of oil are held, when the bottom line is having enough oil so the pan doesn't run dry and oil starvation causes damage. In my thinking, a better means of testing would be to use a sight glass on an oil pan and then introduce a basic set of variables and bring the engine through the RPM band of that specific engine and observe how much oil remains in the pan at the specific RPM's and then engineer/test the changes that can increase the oil level in the pan at a "safe" level without overfilling - otherwise if there were 4-quarts of oil up in an engine while it was running, and we had a 5-quart system, the manufacturers would all tell us to overfill the oil level 2-3 quarts above the factory level to ensure the pan always has a "safe" level of oil. But they don't do that, why? Ya, racer's do it, but I am not talking racers here.

If you ever read any of the older car magazines, and I suspect the contemporary ones as well, many of their tests target an improvement of sorts, but it is also specific to that engine. Wow! If you angle mill a small block Chevy head to "X" degrees you can pick up 20 HP as seen on the dyno. Hmmm. So what good does that do anyone who owns something other than a small block Chevy? If you use this "X" manufacturer's designed pan, this modified brand "X" oil pump, and their matching billet aluminum oil pump extension and shaft, you will see a 32 HP gain at 7,500 RPM from your 440CI engine. Again, what if I don't run a 440? Many of these mags were selling parts that manufacturers were sponsoring and those parts were only tested specifically on a certain engine built a certain way. What would I see in HP gain on my 440CI if it never saw anything above 5,500 RPM's. Answer: about 7 HP. So now is a $500.00 investment for the tested & advertised items worth the 7 HP gain I am going to see in my street 440CI 'Cuda? 1 degree off in my distributor and a 7HP gain means zip.

My point is that even testing that we see in the magazines, both old and new, or the guys over at West Tech, or any other YouTube source needs to be studied, questioned, and decided if what was presented applies to your engine's make & build. Often times it doesn't, and sometimes it can. But the bottom line is a lot of the times it is done for marketing a product - which can quickly flop or fall out of favor because there was a "new and improved" way to do things. My thinking may be "old school" on some things, and even considered conservative by others, but I prefer to stick to facts and traditions that work rather than try and build a better mouse trap. 

What I have presented is fact, but yes, engine at rest. How much oil is held up in the head in a running engine? All depends on the many variable I have listed. But at the same time, there are all those variables/add-ons that many apply to keep oil from flooding out the engine, or flinging it about, and ensuring it remains in the pan. I can't see a car that sees most of its time running on the street at 2,000-2,500 RPM having a quart of oil up under each valve cover - not a factory Pontiac head. But it would indeed be interesting to have a "window" or clear valve covers to observe/measure the levels that are under the valve cover while at speed and RPM. Maybe this will be my next factual backyard mechanic experiment when I get my engine assembled and running. I may make myself a YouTube star yet!


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## AlaGreyGoat (Jul 6, 2006)

Maybe you could have a dry sump setup with precise monitoring. Could tell how much oil was out at any time.

Larry


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## Machinest-guy (Jul 19, 2019)

Good evening,
It is very difficult with a windowed pan to see anything inside. It helps to window both sides and put very high intensity lighting through the area being inspected. It will shadow and glare. It is as much a photographic problem as it is anything else. Valve covers are easier because parts movement is less so oil flow is more stable, but still often violently turbulent. And with valve covers you can make very tall extended covers and use a mild telephoto lens to stand off a camera so it doesn't get wet. This was back in the day when cameras had film and before LED lighting for sure. I messed around with it in the 70's. 

At some mid point in time Jaguar came out with an oil level sensing system for the oil pan - maybe in the 80's - can't recall for sure and that test stuff is long gone. Ford was behind the sensor tech. A half dozen sensors could be stacked up the side of a pan to give you rough approximations of running oil height but for the gauge in a production car the circuit was dampened like a gas gauge electronically with just a single sensor - a "full or low" sort of system indication. 

Various mechanical float and bobber systems have been used similar to what some propane tanks use have been historically tried. I saw one on a brass era Mercedes once. I think whatever GM engineer pushed the 265cid V8 floating oil pump pickup was thinking took that secret to the grave long ago. Sight glass level indicators don't work in modern cars. The pressures in the crankcase are too varable and move an oil column up and down past useful indication. They are good for large marine engines though. Big engines which turn 1000 RPM or so and have tens of gallons and more in the oil sump. 

Now, unless class rule forbid it, if you get into this sort of problem simply convert to a dry sump and be much happier for just 3 times the money of a good baffled pan and pump system. A dry sump tank can have a sight glass if the tech inspector will allow it (no glass rules) But the question is why bother. If your engine runs out of oil between stops and checks, then you have other issues to look into first.....This is sort of a fun thing to mess around with - the operative word being "mess" but a data logger with fast response sensors will catch air going into the pump better and some coated bearings will save you long enough to fix / redesign the pan. Best to all, Ladd


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