Mike "Hubbie" Stearns

Air cleaner size

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since its too cold to work in the garage, I have been doing some research next to the fire place. My 28 Gramm has a continental 15h engine. If I done the math right, it's 525 cu in. It didn't come with an air cleaner. Does anyone have any idea what size it would need?  The carb is 3" inlet. Thanks Mike 

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Just for an example here is a picture of my carb with the flame arrester.  The carb throat is 1 7/8",  the deflector is 4 1/2" diameter and 2" deep,  the neck that goes to the carb is 1 1/2" long. My engine is 200 ci  60 hp @3200. Maybe you can upscale from this.  Some others that I have seen are like a tin can with louvers all around.

$_573.jpg

Edited by Tinindian (see edit history)

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Thanks Tinindian. Here in the Midwest, it can get quite dusty in July till September. I really don't want to run any engine without an air filter. That's why I'm open to ideas of size I should. I found a web site that said to use an air filter that is 6X18 round which seems over kill

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On 12/12/2018 at 9:31 AM, Mike "Hubbie" Stearns said:

Since its too cold to work in the garage, I have been doing some research next to the fire place. My 28 Gramm has a continental 15h engine. If I done the math right, it's 525 cu in. It didn't come with an air cleaner. Does anyone have any idea what size it would need?  The carb is 3" inlet. Thanks Mike 

What is bore x stroke x cylinders(6?) ?

I assume it will be a slow reving engine & poor volumetric efficiency. Say half rev's of  what today's engine do : 525/2 = 262.  And you are unlikely to be running it fast.

Guess you want some thing period looking like or others in that style

https://forums.aaca.org/topic/319764-for-sale-1937-pontiac-and-other-years-air-filter-cleaner/?tab=comments#comment-1819569

 

Edited by 1939_Buick (see edit history)

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My 1929 Cad has no factory air filter. I was told to not even think about one. The carb is designed to not use one and those who have attempted retrofitting discovered that the increased resistance through the filter is like operating it with the choke on and results in a rich mixture. It was just not made for a filter. 

 

My 26 Lincoln has a spinner (propeller) device that centrifugally throws the dirt to the side. Guess there's not much drag in that design. 

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You can decrease the intake drag with a bigger filter up to a certain size, after which the change will decrease per mm extra diameter and length. But determining that size is the impossible task without knowing a bit more about the air flow resistance of air filters.

 

My Dodge 8 has a later oil bath air cleaner on it. Originally they it had a mesh screen (dry) to keep birds out of the intake and a drum to silence the carburettor. In fact it was called a carburettor silencer. Luckily it is a downdraft. The choices are much reduced with an updraft. Any extra tubing you put in will add extra drag to the intake so it needs to be larger than the carb. throat to minimise that drag. It should also be smooth internally, with no wrinkles or sharp (small radius) bends.

 

The spinner or propeller device on the intake also induces drag. The propeller is driven by the flowing air! I am interested to see the pile of dust at the bottom, supposedly removed from the intake air. The propeller may just be a gimmick with a stilling chamber behind it - I remain to be convinced.

 

One very simple thing is to put a stilling chamber in there, like a fuel pump has in the glass bowl. Dust may settle out as the air flow slows. But you have no space for that and it would need to be a good size!

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19 hours ago, m-mman said:

My 1929 Cad has no factory air filter. I was told to not even think about one. The carb is designed to not use one and those who have attempted retrofitting discovered that the increased resistance through the filter is like operating it with the choke on and results in a rich mixture. It was just not made for a filter.  

What about if it is a big one? Most filters I have seen on updraft carb's on sometimes large engines are tiny, about right for a 750 cc engine. Think of the air cleaner on your modern heap, for an engine that is much smaller and burns less fuel and you will be approaching the surface area of filter you need in your Cadillac.

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On 12/12/2018 at 11:31 AM, Mike "Hubbie" Stearns said:

Does anyone have any idea what size it would need?

Not me.

 

But as a first guess, I would look at the size (surface area of paper, perhaps) in an air cleaner on a modern engine of similar size, using the simple assumption that although volumetric efficiency will be greater and the fuel burn per mile will be less in the modern engine, the volume of air gulped down per mile might be similar. After that, go bigger if in doubt!

 

Thank you for this question. I have been pondering for a while how to hide an air cleaner in the Dodge 8 carb. silencer and this has made me review my half baked previous ideas.

Edited by Spinneyhill (see edit history)

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There are some very inexpensive kits on the aftermarket.  Mr. Gasket #4354 for example is less than $15.  Perhaps you could just buy one or two and do some experimentation. 

If you find a setup that works satisfactorily, then you can spend more time and money on it to make it look 'period correct'.  

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29 Cad - Updraft "Johnson" carb on a flathead V-8 means that the air intake is right in the middle of the engine valley. Later Cads (32-33) used a funnel air intake to draw air from the top of the engine area. I think they have simple screens in them  but not sure. 

 

The Johnson carb is not typical (I have no good technical information on it maybe Carb King can add something) but it has an air intake AND a by-pass flap that opens when needed for something. . . . (?)  There is also a throttle plate below (above?) the linkage controlled plate. I have yet to understand it completely. 

This design might also have something to do with the inability to 'simply add' a filter. 

 

The spinner filter is stock Model L Lincoln design. I'll get a pic tonight. In the mean time you can likely find a Model L picture on the web. 

Edited by m-mman (see edit history)

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This is another style of flame arrester on a 29 Pontiac. 

 

 

 

I doubt that there was3470198225_4cef3a1ec4.jpg.9c946d2ca6d76cd1f1ce998cf3396547.jpg

/is any filter material in the canister.  When I put an air filter on my car I could not get the carb lean enough to run properly.  Obviously some of these carbs are designed to operate with little or no inlet restriction.

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1 hour ago, Tinindian said:

Obviously some of these carbs are designed to operate with little or no inlet restriction.

It would be interesting to know the head (suction) loss across a small air filter vs that across a larger one.

 

The losses are related to air flow velocity, so a bigger filter (paper) surface area should have less loss and thus reduction of air flow through it.

Edited by Spinneyhill (see edit history)

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Maybe you should look at racing air filters:

https://www.dragzine.com/tech-stories/engine/modern-drag-racing-air-filtration-should-you-run-an-air-filter/

 

Inter alia it says

“One of the biggest problems is running an undersized filter,” Thomson explains. “I don’t know that there is a true restriction if you choose a filter that exceeds the volumetric requirements of your engine. The performance differential is minimal if the correct filter is used.”

Edited by Spinneyhill (see edit history)

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Calculate the size of air filter you need at K&N Filters, 3/4 the way down the page. Read the page first though!

https://www.knfilters.com/filter_facts.htm

"Use the formula below to compute the minimum size filter required for your particular application. The usable portion of the filter is called the EFFECTIVE FILTERING AREA which is determined by multiplying the diameter of the filter times Pi (3.1416) times the height of the air filter in inches, then subtracting .75-inch. We subtract .75-inch to compensate for the rubber seals on each end of the element and the filter material near them since very little air flows through this area.

A=(CID X  RPM) / 20,839
A = effective filtering area
CID = cubic inch displacement
RPM = revolutions per minute
at maximum power"

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2X on the K&N universal filters (huge amount of styles and sizes).  I have run them for years on my Graham-Paige cars.   I was shocked to see how much dirt they pick up.  I just slip it off at a show and install the original filter....if you can call it that, the manual says wash it out in gasoline and dip it in waste oil to recharge the filter.  My 1929 322cid uses what looks like a soup can, maybe 3 inches round, my 1933 uses a 12 inch round unit.  The originals change the sound of the running engine when they are installed.  I do drive on gravel roads occasionally.

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I finally had time to do the math. According to the math, I would need a 6X7 ( dxh) filter. Unfortunately I won't fit directly on the carb. Ill have to make something to get it to some free space. Will probably use some 3 1/2 or 4 inch tubing since the carb is 3 inch. Mike

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