H gas / kerosene carb differences

Luke9 · Jan 7, 2021

Two questions: What are the differences between the carbs on the H for gas and kerosene?

Can the kerosene carb be converted to gas by jetting/needle changes?

And does it even matter i.e. will a kerosene model tractor run fine on gas only with no carb changes?

I guess that's 3 questions. thanks!

old · Jan 7, 2021

Simple answer yes it will run just fine on gas and if you think about it you have to start it on gas so why wouldn't it run just fine on gas???

rustyfarmall · Jan 7, 2021

The main metering stem MIGHT be the only difference. Venturi, etc. are all the same.

DeltaSteve · Jan 8, 2021

No,the venturis are not the same. gas needs more oxygen,hence a bigger venturi.My F20 was running extremely rich,blowing black smoke.We fought and argued with it to get it leaned out. My
friend,who is an old Harley mechanic figured it out. He took the venturi and 'bored' out the center. It runs way better,doesnt smoke or soot up plugs. And it has more power.

Luke9 · Jan 8, 2021

ok, good to know. Obviously the motor starts on gas, and the book even says you can fill the main tank with gas and run that way but with the caveat that it will "perform much better with the correct fuel" or something like that. For sure, thousands of distillate carbs have been running on gas for the last 50+ years, so its not like it doesn't work.

I was trying to chase through the parts book to pin down what is different, but it isn't very clear. Venturi will be something to investigate then. thanks.

rustyfarmall · Jan 8, 2021

(quoted from post at 09:22:34 01/08/21) No,the venturis are not the same. gas needs more oxygen,hence a bigger venturi.My F20 was running extremely rich,blowing black smoke.We fought and argued with it to get it leaned out. My
friend,who is an old Harley mechanic figured it out. He took the venturi and 'bored' out the center. It runs way better,doesnt smoke or soot up plugs. And it has more power.

F20 carb is not the same as an H carb. I've rebuilt many H carburetors. Venturis are the same in all.

pete 23 · Jan 8, 2021

Venturi is the same. Idle jet, nozzle, main jet originally were.
different. Also the plug(with screwdriver head) on outside that is
in Idle porting may be different. Some are different length .

Bottom line, I would not worry about any unless it doesn't run
decent.

SadFarmall · Jan 9, 2021

From the Blue Ribbon Serviceman's Guide for Farmall-H and 4 Series Tractors and Power Units:
"The International Harvester Model D-10 1-inch updraft carburetor is made in two types. The 50981 DA carburetor is for use with the high-compression gasoline engine. The 45108 DB carburetor is used on the combination gasoline-distillate and the kerosene engine.
[b:c45df12a8e]The principle difference between these two carburetors is in the main fuel adjusting screw seat, the metering nozzle, the throttle butterfly, and the throttle body. Should it become necessary to renew any of these parts, care should be taken that the correct parts are used on each type of carburetor as the operation and fuel economy would be affected.[/b:c45df12a8e]"
Hope this is of help,
SadFarmall

H gas / kerosene carb differences

Luke9

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old

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rustyfarmall

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DeltaSteve

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Luke9

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rustyfarmall

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pete 23

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SadFarmall

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