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Why always updraft..?

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#1 dads706


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Posted 13 September 2012 - 05:21 PM

Just curious, why did all the tractor manufacturers stay with updraft carburators? I would have thought that downdrafts would have been a way to boost HP a bit. But I can also see that it may have caused some design/engineering issues.

Please understand that I am somewhat mechanically challenged.

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Dads 706G, 44 Massey, and a lone 4400 Ford backhoe (Industrial version of a 4000 Utility)


#2 George 2

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Posted 13 September 2012 - 06:18 PM

Hood profile. Hard to squeeze in under the hoods on some tractors.

#3 updraft


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Posted 13 September 2012 - 06:19 PM

Having chosen that feature for a user name, I should be an expert on the subject, but I am not. One reason which comes to mind is the use of an updraft carb keeps it mounted low enough to allow gravity feed from the gas tank. I think F-14 and F 12 used a fuel pump, but most didn't. Lowers production cost with one less needed part.




The lineup:
1927 McCormick Deering 10-20 1930 McCormick Deering 10-20
Farmall 560 gas 1942 Farmall M Farmall Super C
1966 IH Cub IH 340U International 544
1937 Case CC3
1939 JD model H 1941 JD model H 1938 JD model L
1952 Ford 8n Ferg TO 30

#4 tcmtech


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Posted 13 September 2012 - 07:44 PM

Updraft also made for a good way to keep a stuck float from literally filling the whole engine with fuel if left long enough.

Briggs and Stratton used to have their carburetors on their vertical shaft engines set up so that they has a slight up hill climb to get into the intake port but then decided to change it so that the intake port was below the carburetor so that now whenever the float sticks it dumps the whole fuel tank into the engine creating all sorts of problems.

A little change can make a big difference in how something works or does not work when a simple part doesn't do what it supposed to.


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#5 international3088MFD


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Posted 13 September 2012 - 10:04 PM

learned that in an in-direct way when dad and i put a 350 v-8 in my massey harris 44.. electronic fuel pump is necessary to get fuel from tank to carburetor, as the carb bowl sits higher than the bottom of the tank...

WEGMAN FARMS: 325 acres of corn, beans, oats and alfalfa crop rotation.
80 cow Holstein milking operation.

Tractors on the Farm: Case IH MX Magnum 200, MX Magnum 180, McCormick MTX 135, Case IH MX 110, IH 686 D312 diesel, Farmall DX55, Farmall Super M, stage II, Case 650 dozer. Case IH 2144 combine. Run Red

My Tractors: 1972 IH 1066, 1957 Farmall 350, 1950 Farmall H, Cub Cadet 100, Cub Cadet 682. Cub Cadet 149, 1951 Massey Harris 44, 350 V-8 conversion tractor.

SEARCHING FOR: International 966 Diesel. Serial number: 29192
Gone but not forgotten: International 3088 open station w/ Elwood MFD


#6 john e. grott

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Posted 13 September 2012 - 10:43 PM

I'm not positive on this but was told, that the down drafts back then iced up easier also .

#7 New Englander

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Posted 14 September 2012 - 04:19 AM

Updraft also made for a good way to keep a stuck float from literally filling the whole engine with fuel if left long enough.

JD Two Cylinders use a gravity fed side draft and will indeed fill the crankcase with gas if the needle leaks and you haven't shut the fuel valve off. The later series have an automatic fuel shut-off run by oil pressure. I've had one of those fail as well.

In either case you get to do an unplanned oil change. The up-side is the oil stays clean for a long time afterwards!

The lesson I took is only use rubber tipped needle valves. I had the same problem with an International but, as stated, it didn't fill the crankcase, just leaked all over the shop floor. Lesson learned there was to shut the fuel off if parked inside. Also replaced that needle with rubber tipped. I found my local Deere dealer stocks the seal and diaphragm kit for the auto shut-off for a nearly 60 year old machine!