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If a stock A engine produces "about" 3 psi of oil pressure .....

How does the oil get through a spin on, full flow filter?

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Uhh ohh. My gauge reads either 10 or 15 psi I think. Maybe that's not a good thing for me. Now I wanna double check to see what's the deal.

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The kit that I bought comes with a brass tube that fits into the discharge hole which makes the oil go through the filter first before exiting into the lifter valley or valve chamber.

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The "A" oil pump, like almost all of them, a constant-displacement design. Normally the pressure is so low only because nothing is resisting the flow of oil. If the oil must be forced through a filter, the pressure will rise. If the filter got all clogged up, the pressure would rise quite a bit.

Doug

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So, the pump is a volume pump, not a pressure pump and the engine is "loose".

That begs the next question.... does the pump have the ability to create enough pressure to open the bypass of the filter? (especially important when starting with cold oil)

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I would say so. I would think Venturis law of blah blah would be the case. X psi building up on one side and being forced through Y size diameter = Z amount of pressure being released on other side.

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The only way to check how much pressure an A pump, or any pump, will produce is to put a gauge at the end of the oil line and not let any oil pass through, like checking fuel pressure. I have heard it can pump 30lbs but don't know how you would check it on a running engine. However, experience from many users shows it will pass through an oil filter no problem. I have pressure to the center main and a full flow filter. My gauge goes over the 10# mark when cold, 0 at slow speed when hot. I used to worry about it, but since the engine has not failed, I don't worry anymore.

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Model A oil pumps are a very conventional design & flows gallons of oil per minute. They have NO pressure regulator valve, thus, the pressure is low. They have great flow to fill the oil chamber & the baffle plate in the pan, as all the lubricating is done by dip or gravity flow. I read that the pump is CAPABLE of something around 80 PSI. With the proper plumbing, they ARE capable of pushing oil through a FULL FLOW filter.
I, personally, have never seen a Model A oil pump fail, or break, except for a failure in the drive gear, & if that happens, you'll know it, as the distributor won't turn & PFFFFT!!!, that sucker is dead in it's DIAMOND TREAD TRACKS!!!!----(CALL A.A.A. @ 1-800-AAA-HELP) Yes, thet's the REAL phone number!
Bill W.

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They are also the same displacement as the early V8 pumps.
Lawrie

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I once tested a rebuilt stock A pump with drill and simple test rig it flowed 10 litres per minute with no restriction at 1200 rpm drill speed
The same pump also made 93 psi when closed off when the drill was not able to keep turning
a stronger drill may have made more psi ???
Colin

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Hi Guy's


The way the A engine oil system is set -up the oil "port" & the center cam brg is the only part of the engine that get's "Pressure"...Some body said the other day if the center cam brg get direct feed from he pump,,,why is it the most worn...???


Greg out West

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Dirty oil ?

CZ:D

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So, for the most part the purpose of the oil pump seems to be to lift the oil to a higher point in the engine so that gravity will pull it down around all the spinning parts. There is no oil pressure because there is no resistance.

Inserting the filter, in this case, would cause a little back pressure on the pump but not change the overall open flow throughout the engine.

Fascinating

Splish Splish Splash I was oiling A bath.....:D

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As Lawrie noted, the same gears were used in the early V-8's roughly '32-35, in a full pressure system. The V8 system was also much more expansive, of course, feeding 6 shaft bearings and four paired full floating rod bearings...the A pump in a stock engine is only asked to move the oil upstairs but is certainly capable of plenty of pressure if channeled properly.
Pressure in an oil system is simply a matter of volume of oil delivered versus volume leaked out of the delivery system.

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Without the plumbing and modifications at the pump for a true pressure feed Model A system, I don't see how that oil pressure would ever open the check valve in an oil filter. I think the filters that spin onto the conversion valve cover may not have the check valve. I would like to know for sure about that.

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FWIW:

I only had one oil pump break over 50 years ago with my Coupe -- it may have been an A oil pump or a B oil pump -- think I still have it -- had it on a B engine w/Police Head marked "B", B carburetor, & B distributor -- the outer cast iron completely sheared off about midway between the pump gears below & the valve chamber above -- heard nothing when it broke; however, not long after, the front connecting rod bearing started knocking "very" loudly -- was traveling a short distance at over 70 mph while drag racing for top speed as a dumb teenager -- had to swap out this almost perfect B engine & replaced it with a very well used oil burning & smoking A engine.

Model A opinions on different subjects are usually different sometimes depending on one's past experiences -- even though Model A & B oil pumps do not break often, because of this one (1) incident, I installed an oil pressure gauge on my later acquired Town Sedan, with a full flow vertical mounted oil filter so I could "see" whether or not oil was constantly flowing -- one oil pump break was enough for me.

At 30 degrees ambient temperature, oil gauge needle is buried "all" the way to the right; however, needle gradually moves left as engine & oil reaches operating temperature -- appears to be functioning properly.

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Mass A man, As mentioned an A pump puts out plenty of pressure. The A system is like a garden hose. water flows out the end with little pressure. Put a nozzle on it and you get a pressurized stream . The oil filter resists the flow like a nozzle and thus there is pressure.

My A pegs the needle at 15lb when cold. the check valve in the filter is of no concern. To answe your question,I think most filters have a check valve. I use Wix and it does.

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On the full floater Ford bearings on '50's OHV engines...many that were close dimensionally were so converted for racing, and Moon supplied equivalent bearings in sizes for the popular engines that were too far dimensionally from Ford flathead...
The reason...the early OHVS when hotrodded could be made to rev far higher than the factories intended...and ran into a rev limit from catastrophic rod failures. Smokey Yunick eventually analyzed this weakness to the behavior of locked rod bearings in rods that distorted their big ends at high RPM's, a type of failure eliminated by the floaters. Rodders soon went a simpler route with boxed or special aluminum rods for drag cars, and the factories eventually strengthened OEM big ends, but for a while many hot engines could not reach their potentials without floaters...
BUT, I mentioned the floaters in connection with the capacity of Model A sized pump gears. Full floating bearings have clearance on both sides, and so offer more area for pressure drop than locked shell bearings...and the little A type gears had plenty of capacity for that.

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Thanks for your reply John. What I was also really wondering, what exactly is BEHIND that spin on oil filter on the valve cover? How does pump oil pressure get restricted to go into the filter on that Model A engine? Some kind of plumbing is needed, I'm sure, but where?

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Mass Man: The spin on kit has a metal tube that fits into the oil pump outlet at the front of the valve chamber. That tube takes all the oil direct to the filter mount, through the filter, back out and dumps the oil into the front valve chamber resevor, right where the stock outlet put it. Its a neat setup. I put a 90 degree adapter on mine so the filter stands vertically. That way it does not drain down when resting, and is cleaner when changing.

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It's very simple,,look at where the filter assembly is located on the "A"valve cover.It's right at the front where the stock "Oil" system deliver's the oil to the front of the series of built in "Dam's"..


They pick up the oil from the feed pipe & it goes thru the filter & the outlet is dumped in the same area in the first Dam...Hense you end up with a full-flow set-up...



On the "B" engine, Ford improved the A oil system by adding a "Oil Galley" to feed the Main's & Cam brg's...It was still a open system, with the front of the oil gallery feeding the dipper tray & lubing the cam gear on the way




Here's Question ???. What cause's more wear, running without a air filter or oil filter....


Greg out West

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The instructions speak of a pipe that is inserted into the pump output that channels all the oil through the filter and then back into the engine.

And now that the thread is back on topic...

What are the advantages / disadvantages of the two add on oil filter system? (Valve cover vs timing cover)

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Thanks guys for answering me about the oil system. My sincere apology to MrWzrd for butting into thread. I never thought of myself of a hijacker, but I sure did just that!

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Here is what it looks like from the outside of the valve cover. The upper brass fitting has a brass tube behind the valve cover that comes straight from the oil galley and leads straight to the inlet holes on the oil filter. Thought this might give you a better visual aid.
http://pic40.picturetrail.com/VOL301.../408364743.jpg

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Did some exploring on/in the engine over the weekend and found lubrication diagram for the engine. I am constantly amazed at the simplicity in this car.

The engine has absolutely no pressure fed lubrication points. Everything is either gravity or splash lubed, including the mains. (that one surprised me) The pump simply fills the valve cover cavity with oil and it drains through various holes and pipes to the parts of the engine.

So the oil filter is actually just grabbing the oil pump output and putting it into the valve cover cavity after filtering it.

During the exploration (took the oil pan and lifter cover off) I also found my rear main oil leak. The return tube had a big ol' dent in it right about where the label "Oil return pipe" is on the diagram. (also found that the inside was quite clean.... and the peasants rejoiced!) Took the dent out and the engine isn't pumping oil overboard anymore.

Now I have to find out how the timing gear cover mounted filter get the oil from and to the engine.......

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The timing cover partial flow filter was originally designed for engines modified for pressure feed. It taps oil from the hole in the side of block. this is right out of the pump.

This is where it gets confusing. There is actually oil pressure from the pump up to the spinning distributor drive gear. This spinning gear throws oil on the valves and the it drains through the oil dams to front.Clear as mud eh.

The timing cover filter can starve the valve chamber of the oil from this gear if it does not have a restrictor in the line. I would not recommend this filter.

John

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It took a while to figure it out but it looks like the timing gear cover filter is a bypass filter not a full flow.
John, your comment basically confirms this. And I am very familiar with bypass filters on my diesels.
Just pulling the plug out and putting the line for the filter in can have one of three consequences. 1 - it will divert all or most of the oil through the filter and starve the valve cover cavity. 2 - Minimal or no oil will flow through the filter. (oil will flow through path of least resistance...pump outlet in valve cover cavity.) or 3 - Oil will go to both and the world will be a happy place.

I concur that this would not be the recommended way to add a filter. First is it not doing full filtering and second, it can starve the engine of oil.

The valve cover filter would be the way to go since it does not change where the oil is going, it just runs it through the filter as it comes out of the pump. If the filter were to become clogged the pump is capable of producing the pressure to push the bypass open so oil starvation should not be a concern.

Decision made...gotta pull a few pennies together ....

Thanks for all the input.

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And now I know why this tube is in the valve train. I was surprised to see it when I did a valve job recently. This was "Greg out west's" car that I own now after he passed about 6 yrs ago.

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The standard modern oil filter has a check valve that prevents oil from draining back into the crankcase. It takes a certain amount of pressure to open the check valve. Filters for hydraulic systems do not have the check valve and will flow oil with very little pressure. The hydraulic filters are used on Model T's which only have the flywheel to move oil around (no oil pump) so very little pressure.

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I have the full flow valve cover filter from Mike's and it works well. Your oil will stay clean and this will be noticeable. I use Shell Rotella T6 15w40 and it will get changed at 2500 or once a year. You need to look for filters that have a valve that opens at I think 8 to 12 psi however you can also take a drill to the round holed that go along the center of the filter. This effectively removes the valve and removes the resistance with it.

Ron

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I saw that video and had a similar reaction.

I think people confuse the anti-drainback valve, which is the silicone membrane that you can see inside the ring of holes around the filter and which people sometimes recommend puncturing, with the bypass valve, which is a little spring way in the back of the filter. The bypass valve is the one that has the PSI rating of 8 or 13 or whatever. It opens only if the pressure inside the filter exceeds that rating. This is useful when the engine is cold in order to get oil to the engine quickly; a Model A oil pump can easily pressurize cold oil above the PSI rating of normal bypass valves. Otherwise the bypass stays closed and oil flows through the filter media, past the ADV, and back into the engine. The ADV has no PSI rating, it opens at any positive pressure at all.

I have no idea where this "check valve" terminology came from or why people got it into their heads to drill holes in perfectly good filters.

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Unfortunately a lot of people are going to see that video and believe it and some other misinformation.

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On most oil filters the bypass opens at 6-12 pounds

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The bypass valve bypasses the filter if it gets stopped up preventing oil starvation. It reacts to the pressure drop across the filter media not the oil pump delivery pressure.

https://www.pgfilters.com/tech-tips/...ve-oil-filter/

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It's both, really. Per your link:
The valve is designed to open when the oil filter becomes clogged or when the oil is too thick.

Bottom line, the bypass/relief valve opens in any situation where the filter media restricts the oil flow enough to create that 8 psi pressure differential.

Finding the psi rating of the bypass valve can be kind of a pain. It's published for some filters but not for others.

For example, here is the oilfilterdata.com page for the Wix 51515, which is a common choice to use with the valve cover oil filter setup. You can see the bypass valve on this unit starts to open at 8 psi, and then is fully open at 16 psi.

But other filters are different. The Purolator L30257 opens at 20 psi and the Wix 51355 opens at 33 psi. That might be above some folks' comfort level.

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There are real problems with some filters where the filter media is really thick, so there's an upper limit to how fast oil will transit the filter. Mobil1 filters had a bad rep, back when I was on the BITOG forums, for being too restrictive with flow, causing the bypass to open frequently. But that's a whole different issue from what we're discussing here.