Flathead oil gallery

[m606paz]

Hi Boys!
I have doubts about the lubrication galleries in my flathead, since I am not going to disassemble this engine now.
The motor has a hole with horizontal outlet pressure, with outlet to the left. Then there is a hole in the middle, with vertical outlet, to install the oil pressure sending unit. Those last two communicate.
There is a third hole that we normally see covered with a plug, but in my case, it was the oil filter return.
There is no communication between outlet and return holes...
Does this last return hole need oil pressure?
My engine no have valve relief.... is a 1944 model.
Thanks in advance!

[Jacques Reed]

Hi Mariano,

Your diagram shows a factory full flow oil filter set up. I have never seen that relief valve setup other than in diagrams. Every WW2 Flathead V8 that I have seen in Australia has the bypass type filter. Hot rodders have for years modified the system on Flatheads to incorporate a full flow oil filter utilizing those three inlet/outlets.

Most early factory Ford flathead oil filter setups are the bypass type. This type does not filter all the oil but only a small proportion of it which is returned to the sump (i.e. oil pan) from the filter outlet.

The inlet orifice size on the bypass type oil filter container is critical to maintaining oil pressure within the system. Under no circumstances should it be enlarged in the belief it will filter a larger volume of oil. to do so would cause a substantial drop in oil pressure in the system.

Would be curious to know if anyone has one of those relief valves.

Cheers,

[m606paz]

Jacques , thanks for your reply!
How about grub screw,Does it have to be screwed into the hole or not?
Does the third hole need pressure oil?
Regards!

[rob love]

The grub screw will usually have a small hole running through it to allow some oil in case the filter gets plugged or the lines get kinked. There is no pressure relief built in to those old filters, and dirty oil is still much better than no oil. Besides, even that system is not a full flow oil filter since oil goes to the rear main before it goes up to those fittings.

Without the grub screw, you have all the oil (less what already went to the rear main bearing and into the back part of the crank) going across to the main gallery. The CMPs I have worked on take a small portion of that oil into the oil filter and dump it back into the pan.



I cannot say what was in use in late war vehicles, because the bulk of Fords in Canada are 43 and earlier. I don't see many 44 or 45 dated Ford CMPs around here. I think they were needed overseas. However, the system shown in the second photo you show I believe would have had a fitting that reached down into the hole and blocks transfer across to the main. If you blow the photo up much larger you can make it out. The external bypass looks like that used in the carriers. Again, I have not run into that in the domestic CMPs, but then again I have not seen it all.

[Jordan Baker]

This previous thread may answer your questions.

http://www.mapleleafup.net/forums/sh...ad.php?t=20460

[Jacques Reed]

Thanks Jordan, Rob, and Lynn,

That makes it all very clear. I have never seen a bypass valve on the oil filter lines a CMP truck here in Australia even though it is shown in the Truck Maintenance Manual. Just a carrier requirement perhaps with a semi full-flow system? My mistake calling it a relieve valve.

The Parts List for an F-15A makes no reference to that bypass valve either. It only shows the bypass filter setup and oil filter lines from the block and to the sump.

Very good information which could prevent a lot of damage and heartbreak.

Cheers,

[Lynn Eades]

So Mariano, tell me what you intend to do with regards to an oil filter in your truck?
I assume you intend to run a bypass filter?
If this is your plan, then just tap into anyone of those 3 holes. All you are doing there is receiving oil under pressure.
I doubt that there is a plug (or restrictor) inside the horizontal gallery (where you picture shows the grub screw) If so, TAKE IT OUT.
You bypass filter will have (or should have) a restrictor in it somewhere(see Jacques post)
You need to return the oil from the filter back into the sump (Robs post) or through an oil filler tube with an oil return fitting in it.(Ford made them)

There is absolutely nothing wrong with a bypass filter. They normally have a finer media and remove more nasties. About once every 10 or 15 laps of the oil, it all gets to go through the filter, so over time it is all nicely cleaned.

The war time engines were swapped around a bit between trucks and carriers. This was o.k because there was nothing (no restrictor or plug) in there, in a Canadian or British carrier (the clever fittings did the job of restricting the flow, and sending it via the cooler). The complications came along with the Australian pattern carrier set up (same plumbing, different fittings, which required the restrictor plug) and the hot rod boys fitting full flow filters.
I hope that helps.

[m606paz]

Thank you all for your comments.
As you know, I do not have command of the English language, only the basic one, so it is difficult for me to write what I want to comment on.
After analyzing everything they have written and seeing that my engine had installed, before I had had a modern full flow filter system including an oil radiator, elements that I removed, because it is not the original configuration I am looking for.
But I find that they have installed a grub screw as shown in the previous drawings, which I will have to remove, and in that way to have oil again under pressure in the internal horizontal conduit along the engine that lubricates the crankshaft and connecting rods.

[Lynn Eades]

Hi Mariano. If you have nothing connected to your engine block (apart from an oil gauge) then you must remove that plug. It interrupts (stops) any flow from your oil pump to your bearings. It MUST be removed. You also have to make sure there is no loctite or sealant bits left in there to damage your bearings. If you have a bypass oil filter connected, you still remove it. Your first picture only applies to a FULL FLOW filter. In that case, the plug stays in. Be careful to understand what happens.
Thankfully your English is very good. If you spoke one word in your native language, I cannot understand.
Ask whatever questions you want to ask. I can only offer advise. I am trying to be clear.
The responsibility for what happens is on your shoulders. If you were next door, I would come over and help, but that cannot happen.

Ideally the grub screw / gallery issue should be decided while the block is bare (completely stripped)

[Lynn Eades]

Here are photos of the two alternatives (options) for the oil bypass filter return. Some sumps come from the factory with a fitting welded inthe side of the sump.

[Jacques Reed]

Thought this might be of interest:

As discussed, the orifice size on a bypass filter, or the orifice size in a grub screw when used in a semi full-flow filter, has to be very small to maintain oil pressure within the system.

I head read somewhere what the orifice size was on the bypass filter but cannot find it again. Not even sure if the size was factory info or someone's best measurement.

Thought I would see what it was on a spare bypass filter body I had laying around.

I used a set of numbered drills to check the hole size and my best estimate is a No.56 drill size which is 0.0465" diameter.

Unfortunately my No.55 drill is missing but a No.54 drill shank is too large and does not enter the hole so it could also be a No.55 which is 0.0520".

The difference between a No.56 and a No.55 drill is only 0.0055 so No.56 could still be the size as there is almost no gap around the drill in the photo. Whether that small difference would be critical is another matter.

In simple metric terms the hole is between 1.2 mm and 1.3 mm so any enlargement of it is not good for oil pressure.

Cheers,

[m606paz]

Originally Posted by Lynn Eades

Here are photos of the two alternatives (options) for the oil bypass filter return. Some sumps come from the factory with a fitting welded inthe side of the sump.

Hi Lynn
Thanks for the pics. The return on late flathead filter go to sump...

[m606paz]

Originally Posted by Jacques Reed

Thought this might be of interest:

In simple metric terms the hole is between 1.2 mm and 1.3 mm so any enlargement of it is not good for oil pressure.

Cheers,

Jacques, thanks for your help!
Great info to know the hole diameter!

[Lynn Eades]

On a finer point, from memory, the volume that flows through a jet is not only dictated by the diameter of the orifice, but by its length as well.
Good info though Jacques.
For example the flow from the end of a long garden hose does not equal that from the tap without the hose connected.

[m606paz]

This is the home made grub screw found in the oil gallery

[m606paz]

This engine had enlarged holes diameter to put full flow oil filter and oil radiator. Now have original oil filter and pipes.