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From Renner's Corners site

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  • From Renner's Corners site

    ALL of the carburetors released by Ford for use on a Model A or B
    had the float bowls EXTERNALLY vented.
    So the use of an air cleaner of any type will negatively affect the air to fuel ratios.
    These carbs were not designed for air cleaner use.
    To allow the use of an air cleaner the bowl vent must be relocated to the INSIDE
    of the carburetor near the choke plate area.

    This is called pressure balancing.

    Unless you are driving mostly on dirt roads you do not need an air cleaner.
    It would take a lifetime to wear out an engine with the dust that's on our roads today.

    3 ~ Tudor's
    Henry Ford said
    "It's all nuts and bolts"

    Mitch's Auto Service ctr

  • #2
    This is a circa 1930 after-market Air Cleaner made by United Mfg, Chicago. It is not a 'pass-through' (obstructive) type of air cleaner. Rather, 'most' air particles drop out of the air flow due to the centrifugal force created by the spinning impeller. As long as the air path between the air cleaner and carburetor is kept large enough, there is no (or very little) flow restriction, so the air/fuel ratio and the pressure in the carb remains the same.

    This centrifugal type air cleaner is not as effective in removing particles as a more modern pass-through type air filter, but it WAS designed for 1920's-1930's cars using the type of carburetors Mitch describes above.

    I was told that some Studebaker's of the '20s were factory equipped with centrifugal type air cleaners. Also, I know that some military helicopters of the '80s used a similar technology for turbine engine inlet sand removal, maybe they still do.
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    Senior Member
    Last edited by Ayyy; 04-25-2018, 03:37 PM.


    • #3

      1. Out of really not knowing any better, and not following instructions, if any, I connected my Hi-Boy 6" tall K & N filter to my "early" untouched Model B carburetor, where on paved back roads, in stop and go traffic through small towns, I have averaged (20) MPG with my 1930 Town Sedan, after monitoring for the first 2,000 miles, after having installed new rings and new pistons, and installed a new 330 Stipe cam, in conjunction with a Police HC Head and a newly installed 3:27 gear ratio, with 550-19 radial tires.

      2. I have no idea if MPG's would change if I used this same Hi-Boy 6" tall K & N filter with my other newly rebuilt Model A Zenith carburetor, my untouched Model A Tillotson that came with this Town Sedan; or my old untouched Marvel carburetor that came with my Model A Coupe 60 years ago where I got well over 20 MPG with then "unleaded" Pan-Am gasoline.

      3. Over the past (20) years of reading different Forum reports and different written articles about carburetor venting combined with filters, appears maybe one day someone will try one (1) filter arrangement on several different Model A & B carburetors on the same engine, in the same car, with same tires, and driving conditions, and report actual mpg's for each different carburetor.

      4. Another good actual experiment would be to find someone who just bought a new expensive car, literally beg him/her on your knees to entirely remove their air filter, and report back and compare piston/cylinder engine wear after the first 100,000 miles or so.

      5. No matter the final actual results, it always appears that actual hands-on experimentation with the same owner, same car, followed with a written report is always the most interesting.
      H. L. Chauvin
      Senior Member
      Last edited by H. L. Chauvin; 04-25-2018, 07:03 PM.


      • #4
        I have driven my tudor many thousands of miles since I bought it in 1975, and have never used an air filter.
        Eastern Connecticut


        • carolinamudwalker
          Senior Member
          carolinamudwalker commented
          Editing a comment
          I just changed the cabin filter on my modern. I would not want all that crap in my lungs or my engine

      • #5
        I had an Air Maze air filter on the '29 Tudor, with a Tillotson Carb. One day it fell off somewhere on a highway, the set screw had dented the carb inlet enough to vibrate off. The car ran much better after that and I never replaced the air cleaner. Drove the car about 10,000 miles over the next twenty years with no issues whatsoever.

        I would only use this one on a Zenith, I'd hate to lose it!


        • #6
          I don't have a air filter and I get 10mpg(approx cause I don't check, just fill it when the gauge says zero) because I continually drive it like I stole it.
          You wana look waaay far up da road and plan yer route because the brakes are far more of a suggestion than a command!


          • #7
            Always so very interesting to read about individual Model A owners most sincere, different actual Model A experiences ....... usually when no two are alike, it makes it all the more informative and more interesting.


            • #8
              I've tested 3 types of air cleaners on our Allstate /Marvel carbs.primarily with a vacuum tester and mixture adjustments at approx. 2000 ft. elevation. The least restrictive to the air flow was the 5.5"/ 6" K&N which is now used and no perceptible change from running without a filter.. The worse was the Air Maze paper element. The float bowl vent opening on these carbs is up on the vert. throat area below the manifold flange.
              Senior Member
              Last edited by plyfor; 04-25-2018, 07:16 PM.


              • #9
                I bought an air maze filter 35 years ago and it never made it to be mounted on a carb, remains a shelf piece


                • #10
                  With the amount of miles I do on unsealed roads, I run an air cleaner and I pressure balance the carb. Economy is unchanged and I have that warm feeling that I'm doing both the motor and myself a favour..


                  • #11
                    [QUOTE=Mitch;n78533Unless you are driving mostly on dirt roads you do not need an air cleaner.
                    It would take a lifetime to wear out an engine with the dust that's on our roads today.

                    Not sure about the time to damage or not, but my coupe seemed to run rich with a filter. Black smoke on acceleration and fuel smell. After balancing, it seems better. I did not check fuel economy.


                    • #12
                      I'm confused. Air cleaners were a Ford offered/available option on Model B's and Renner's even sells a few parts for them. (?)


                      • #13
                        Perhaps the statement made by Renner's is too broad:
                        "the use of an air cleaner of any type will negatively affect the air to fuel ratios"

                        Maybe the addition of a qualifier would make this statement more accurate:
                        the use of a restrictive type of air cleaner will negatively affect the air to fuel ratios".
                        The word 'restrictive' being the qualifier here.

                        Air cleaners using paper or foam elements could be considered 'restrictive'. The silencers and screen type air cleaners (optional Model B) would have very little, if any, restrictive properties.


                        • #14
                          Most writers usually agree that on second thought, some of their statements require corrections.

                          After experimentation, Reply No.13 is correct in that only a "restrictive" filter is harmful. After witnessing laboratory test results, most would agree that this statement needs to be corrected in that the size, density, and/or surface area of any filter makes a huge difference.

                          Knowledgeable engineers designing functional sizes and restrictions for air-conditioning filters are aware that if any type of filter has enough openings to freely allow air passage to meet the demands, that there is "no" restriction.

                          For some, only seeing is believing ...... like show me .................. well, just for kicks and giggles, try starting up your home air-conditioner and totally cover your home air-conditioning air filter in your house with about four (4) layers of newspaper pages and please let us know what happens after it runs all day long.

                          After thinking about it, the functioning of carburetors fitted with small Model A paper filters sold by vendors is not much different than your home air-conditioning filter fully covered with newspaper.


                          • #15
                            Looks like yesterday, somebody placed this above initial statement in our National News.

                            "Unless you are driving mostly on dirt roads you do not need an air cleaner.
                            It would take a lifetime to wear out an engine with the dust that's on our roads today."

                            Well, yesterday I heard that someone checked out 14 local new car dealerships and all of their dumpsters were loaded with brand new air filters taken from their un-sold new cars after they read this statement.

                            They also heard that after same was reported on radio programs, Wal-Mart reported that their gas station had to dump their garbage cans all day long to get rid of the new and old car air filters that car owners were discarding all day long ...... even if car owners were not buying gasoline.

                            Did anybody else hear that car owners are rushing to get rid of their expensive and useless air filters?


                            • H. L. Chauvin
                              H. L. Chauvin
                              Senior Member
                              H. L. Chauvin commented
                              Editing a comment
                              Just also heard that every since old oil bath carburetor filters became obsolete, newer cars and trucks began traveling between 100,000 miles and 200,000 miles without smoking or burning oil ...... everyone thought the lack of engine wear was because of newly developed laboratory tested modern filter elements ...... wrong ....... clean highways is the key.

                            • H. L. Chauvin
                              H. L. Chauvin
                              Senior Member
                              H. L. Chauvin commented
                              Editing a comment
                              Just heard two (2) other another reports on useless air filtration

                              A. Costly air-conditioning filters in homes are no longer needed for homeowners who have vacuum cleaners and where homes are occupied by folks who only work indoors.

                              B. In arid regions where it seldom rains ......... and/or where highways go pass dry sandy areas with wind blown sand .......... sharp silica sand kicked up by moving vehicles is no longer harmful to Model A engines without air filters because the sand is now treated by the EPA with non-detergent oil lubrication where this lubricated sand can help prolong the life of Model A engines.

                          • #16
                            A balance tube is easy to install for using an air filter.
                            I'd insert a 1"long thin wall brass tube into the carb bowl vent, then run a rubber hose from that to any point inside the filter element.


                            • #17
                              I’ve wondered why ford didn’t install air filters also. My non engineering mind has thought about the under hood aerodynamics, with engine pans making the air flow back and away from the carb inlet. The hood sides allowing the air to flow out away from the carb inlet. With the carb inlet facing backwards, doesn’t the air have to turn 180* to inter the carb, letting or making the dirt fall out of the air stream? Thus providing clean or cleaner air for the engine? Wish we could ask ford engineers!
                              I have a high boy filter with a tall filter because no engine pans installed nor hood installed as of to date.


                              • #18
                                In trying to place ourselves in the era of the early 1900's, I would think that with an individual or a family advancing from a very slow moving vintage horse drawn buggy, (while inhaling horse blown fumes), to a horseless carriage was such a novelty at first that anything faster and anything horseless was like traveling in Heaven with or without engine filters.

                                Appears oil filters and air filters came a bit later after this initial wonderful type of travel shock wave where engineers were looking towards engine longevity refinement.

                                I remember my Dad talking about mule drawn covered wagons passing in front of his house ...... my son now lives in this house ...... what an upgrade he witnessed for traveling .......... traveling type progress may never end.


                                • Ayyy
                                  Senior Member
                                  Ayyy commented
                                  Editing a comment
                                  ..."traveling type progress may never end."
                                  I hope that's true, as long as its not at the cost of sacrificing our history.

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                                I’ve read a number of opinions on this, and, after just installing a highboy K&N air filter, am wondering if I need to worry about this. From what I’ve read, all that is required to air-balance a Zenith carb is to drill one hole...this sounds pretty simple - does anyone know if this is correct, and, if so, where the hold should be drilled ??

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                                by conaway2
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                                by Bob C
                                Found this tidbit in the Feb. 28, 1930 Chicago Service Letters.
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                              • DaWizard
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                                Ok, I have someone who insists on using an Air Maze filter and I would like to know which K&N filter element is used too replace the restricting element that comes with the Air Maze?
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                                I could not find anything regarding this topic in Search.

                                Which, if any, air filter do you use on your “A” and would recommend?

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                              • dmdeaton
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                                by dmdeaton
                                So lets say we have done the balance mod on the carb and we want to use a air cleaner. What is a good one to use? What about the issues with possible raw fuel fires?
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                                Providing a groove from the float bowl to air intake, modifying the venturi, and plugging the float bowl vent hole.

                                If yes, perhaps could do yourself with a Dremel?

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