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01-23-2016, 01:02 AM | #1 |
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Model B Carb. on a Model A - pros & cons ?
With their vast experience and years of knowledge - I thought I would ask Ford Barn Forum contributors their ideas and input on the question:
If I use a standard (stock) Model A intake manifold, what would be the "pluses" and the "Minuses" of using a Ford Model B carburetor ? |
01-23-2016, 01:34 AM | #2 |
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Re: Model B Carb. on a Model A - pros & cons ?
Not enough to gain to make it worth the switch. Model B carbs don't seem to stall at stops like many A carbs do.
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01-23-2016, 01:53 AM | #3 |
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Re: Model B Carb. on a Model A - pros & cons ?
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What's right about America is that although we have a mess of problems, we have great capacity - intellect and resources - to do some thing about them. - Henry Ford II Last edited by Mike V. Florida; 01-23-2016 at 02:00 AM. |
01-23-2016, 02:23 AM | #4 | |
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Re: Model B Carb. on a Model A - pros & cons ?
Quote:
Is there any reason to bore an A intake instead of using a B intake? Charlie Stephens |
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01-23-2016, 02:54 AM | #5 | |
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Re: Model B Carb. on a Model A - pros & cons ?
Quote:
If one were to do a search for Model A and Model B intakes the A intake is far more available.
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What's right about America is that although we have a mess of problems, we have great capacity - intellect and resources - to do some thing about them. - Henry Ford II |
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01-23-2016, 03:54 AM | #6 |
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Re: Model B Carb. on a Model A - pros & cons ?
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FWIW: In many cases, most Model A owners have lots of respect for "all" of the "different" Model T/A/B opinions of others, mainly because these opinions are for the most part based on "real" past experiences. And, almost every Model A/B question just never has one (1) cut and dry response. I think that after 80+ years or so, some could possibly find a B carburetor on E-bay that someone found under his neighbors hen house, buy it, and wonder why they get 10 MPG less than the A carburetor someone found on an abandon turkey farm under an out-house. Intake size as mentioned often can affect performance, "especially" at higher speeds when one can hear the carburetor intake whistling. I used to talk to Mr. Charlie Yapp often years ago, and in his "Journal of Secrets of Speed Society", he listed very interesting and informative articles written by Henry Miller, Jim Brierly, Murray Fahnestock, Paul Moller, Bob Rentz, Ron Kelley, Urb Stair, and several Model A "improvement" articles from the 1930's Popular Mechanics and Popular Science. Mr. Yapp also wrote this years ago: "When Ford redesigned their four cylinder engine, for the third time , (T, A & B), one of many changes incorporated to increase horsepower was the new Zenith updraft carburetor. This cast iron carb has larger air intake, and exit ports, a larger venture, and most importantly, a power jet that kicks in at higher speed." The B has an intake of 1-1/8" diameter in lieu of the A's 1" diameter ..... a mere 1/8" difference .... but wait ...... what happens when Mr. Pi x and Mr. R-square attacks this 1/8" ..... i.e., 3.14 x .5 x .5 = .785 sq. ins. for the A intake; vs 3.14 x .563 x .563 = .995 sq. ins for the B intake; where .995/.785 = over a 26% increase in a B carburetor's intake's "area" for the engine's fuel mixture flow. Existing conditions of 80+ year old A/B carburetors mixed with repro and original jets can also result in many different experiences and many varying opinions. At higher speeds, a properly re-built B ...... or an original B right out of the box should perform better. Last edited by H. L. Chauvin; 01-23-2016 at 04:01 AM. Reason: typo |
01-23-2016, 07:50 AM | #7 |
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Re: Model B Carb. on a Model A - pros & cons ?
I have a B carb on my tudor, and the increase in performance was noticable, even after having several A Zeniths and a few Tillies on the car over the last 49 years. It also does not faulter during a quick stop.
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01-23-2016, 10:27 AM | #8 |
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Re: Model B Carb. on a Model A - pros & cons ?
I have a B Carb on my speedest, along with a B Head. I had a local machine shop bore out the A manifold. it runs well and stops well. A well adjusted A card was replaced. How you drive and how you adjust your system will provide a increase in horse power. The B intake manifolds I found were to costly for my project. It only cost 25.00 for the bore.
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01-23-2016, 11:36 AM | #9 |
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Re: Model B Carb. on a Model A - pros & cons ?
I've bored out a few manifolds in my time and I'm a believer in the bored A manifold with the B carburetor. The only additions I can make are That I prefer a 1 9/32" (1.281") drill.
If you look at the thickness of the casting, you'll notice it's walls are getting mighty thin.Then you're going to drill them out a little further? I like a 1.281 that cuts a little oversize and the polish it lightly, taking a little more at the bottom. Why? Because of the Bertoli's venturi principal. Don't "Bellmouth" the top of the bore. Progressively enlarge it as you go down to the bottom. Then turn the manifold around and polish the other ends, those that go to the block. Putting your finger up the the holes, you can feel many casting flaws that will impede the flow of the gas/air mixture. Polish these out so the sides are smooth. Curiously, you don't need a mirror finish, just smooth. There is a big "Debate" going on, in which one side says it must be mirror quality and the other says that slightly rough walls (Very small scratches) help with the atomization and mixing of the gas/air. Who Knows? Both sides have their reasons. By tests, this should gain you about 3-4 HP, considering that the Mod A engine is 40 HP, that can mean about a 10 % increase. Definitely worth the effort! Terry |
01-23-2016, 11:43 AM | #10 |
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Re: Model B Carb. on a Model A - pros & cons ?
I had a B carb on my huckster and it seemed to use more gas that the A carb I now have on it. Did not notice any difference in performance but the manifold was standard.
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01-23-2016, 12:35 PM | #11 |
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Re: Model B Carb. on a Model A - pros & cons ?
FWIW: B Carbs on Marine Engines
In the 1930's, outboard motors had antiquated 1930's varnish covered wire coils that would soften and short out with heat. Immediate re-starting of old early 1930's outboard motors was often difficult, where one had to allow the coil(s) to cool prior to re-starting. Few fishermen, sports and/or commercial, would tolerate paddling home in the dark, or worse, in rain storms, so it became popular to install far more dependable 4 cylinder Ford engines in fishing boats. Then, sports fishermen usually traveled at two (2) speeds ....... wide open ..... to and from their favorite fishing spot ........ and ..... stop .... to fish. It did not take long to learn that with a four cylinder Ford A/B engine, at "wide open", a B carburetor could attain higher speeds on an A or a B engine. My all original B carb, with original jets, came from my Uncle's B marine inboard engine. As mentioned on a previous post, I get 20 MPG with this "unrestored" original B carb on my Town Sedan ..... never tested my Town Sedan MPG with my rebuilt A Zenith, my Tillotson, or my Sears Marvel. |
01-23-2016, 12:41 PM | #12 |
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Re: Model B Carb. on a Model A - pros & cons ?
I have one for the last year and a half and do have a bored out manifold and love the B, i see better gas milage, better pickup, more top end speed and easy to maintain, NOW i do also run a B distributor with the built in advance and i am sure that also makes a difference. Bought them both from Renners Corner...
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01-23-2016, 01:08 PM | #13 |
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Re: Model B Carb. on a Model A - pros & cons ?
Per Mr. Terry's post #9, in calling Mr. Ron Kelley and Mr. Charles Yapp years ago, according Mr. Kelley's very detailed experiments in documenting engine performance dynamometer tests, they agreed if one wants a single, very inexpensive increase in HP, just remove the rough cast iron insides and sharp corners of the intake and exhaust ports, which will allow more and faster velocity flow of the "already" atomized fuel.
In my opinion, further mixture and slowing fuel velocity with rough friction surfaces inside engine ports is not required ....... e.g., a Model A/B carburetor works like our old Flit Gun ..... once the Flit liquid is atomized, one does not need to stir and beat up this mixture with a boat paddle to kill mosquitoes on a distant wall. |
01-23-2016, 01:21 PM | #14 |
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Re: Model B Carb. on a Model A - pros & cons ?
I do like the B carb. It doesn't stall at sudden stop. Also I never use the GAV, while starting or out on the road. I do have flow tested jets from Renner's.
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01-23-2016, 01:52 PM | #15 |
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Re: Model B Carb. on a Model A - pros & cons ?
FWIW: Hope this helps if one has a malfunctioning early B-1 Carburetor, (or even an A carburetor), flooding at instant stops:
I have what Mr. Paul Moller referred to in Chapter 9 of his Volume 2 Book as the earlier B-1 Model B carburetor, with the "drum shaped float" which used to flood the vehicle's engine and cause the engine to stall upon sudden stops, similar to that of the round bottom Zenith A carburetor. Stalling immediately stopped once and for all ........ but, after following Mr. Rex Reheis's recommendation, i.e., in his book, to adjust the A or B carburetor float such that the fuel level in the carburetor bowl is 5/16" lower than that of Ford's recommendation. |
01-23-2016, 04:47 PM | #16 |
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Re: Model B Carb. on a Model A - pros & cons ?
The 30 fordor I had came with a B carb.
Was really snappy, the car like to run. Yes I ran it 55 all the time, it was happy. I didn't like having a B carb so I put a well rebuilt A carb on and I could not find a difference. I did not keep track of fuel miles on that car. Just stepped on the gas and went. |
01-23-2016, 08:37 PM | #17 | |
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Re: Model B Carb. on a Model A - pros & cons ?
Henry, I wish I had detailed results of my own! That not being the case, I recalled someone posting Vince Falter's (I think it was) testing that produced the numbers. There is every reason for the B carb. to be superior to the A carb.
1) as you said before, The 1/8" larger dia. throat that allows approximately 25% more air more into the engine. This has to be worth something. 2) The last evolution (B-3 ?) that has the rectangular float, mounted 90deg. to the longitudinal axis of the car certainly corrects the problem of of stalling at stops. 3) The acceleration jet. I believe the addition allows for leaner running. If someone knows about these tests and results, I would appreciate if they could post the link. I think it was Vince Falter, maybe I'm wrong. Terry Quote:
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01-23-2016, 09:06 PM | #18 |
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Re: Model B Carb. on a Model A - pros & cons ?
I'm intending to change from A to B carb and manifold. I have two B manifolds, one with vacuum port at the rear and the other a large one at the front. Who knows why?
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01-23-2016, 09:33 PM | #19 |
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Re: Model B Carb. on a Model A - pros & cons ?
Bruce,
The manifold with the vacuum port at the front (which is what I have) was intended to supply a vacuum operated clutch, the idea was scrapped, the next version a small port was in the rear, both manifolds will work Ok. Go to Vince Falters Fordgarage, much to learn from it.
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01-23-2016, 10:24 PM | #20 |
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Re: Model B Carb. on a Model A - pros & cons ?
Model,A's were built,with a zenith if it is a good carb nothing will run and idle better it was specially design for your car
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