Victory! (carb/governor problems)

Sean0918 · Aug 18, 2011

Thanks to everyone who helped. traced the problem to the governor. I must have done something (although I don't see how) to the governor when I took the carb off. I took apart that top linkage. The rod that extends up from the governor was slightly bent. I put it back together so that that rod would get just a little more "down travel". In the end I think just messing with it freed it up. Anyways, she starts right up and purrs nice and soft now. No more angry growl.

On a side note, can anyone explain why the manifold just above the carb gets cold (like real cold) when the tractor runs. I am thinking it has something to do with compressed air but I have no clue really.

Thanks again!!

JRSutton · Aug 18, 2011

You would be correct.

Law of thermodynamics: increased pressure in a gas = increased temperature. And vice versa decreased pressure = decreased temperature.

So air from going from high to low pressure = cold.

FC Andy · Aug 18, 2011

The manifold gets cold because heat is removed from the air to vaporize the gasoline. Your carburetor has a Venturi in it, this is there to increase the velocity of the incoming air and thereby pull a mist of gasoline into the air. As that mist vaporizes, the manifold will get cold. This is perfectly normal,and expected. Some of the larger gas tractors will actually ice over the outside of the manifold and carburetor in the right conditions. -Andy

Jason the Red · Aug 18, 2011

Good to see you got it going. Always nice to see the solution to a problem also. I've cruised through the archives more times than I can count looking for different items and it is always nice to see a solution, not just a bunch of valid guesses.

Owen Aaland · Aug 19, 2011

(quoted from post at 18:30:10 08/18/11) The manifold gets cold because heat is removed from the air to vaporize the gasoline. Your carburetor has a Venturi in it, this is there to increase the velocity of the incoming air and thereby pull a mist of gasoline into the air. As that mist vaporizes, the manifold will get cold. This is perfectly normal,and expected. Some of the larger gas tractors will actually ice over the outside of the manifold and carburetor in the right conditions. -Andy

While fuel vaporization does add to the cooling effect in the manifold, by far the greatest cause for temperature change is the change in air pressure.

If it were caused by fuel vaporization the manifold would be coldest at full load when the most fuel is vaporized and a small pressure change rather than at low idle when there is little fuel vaporization but a large difference in pressure.

Janicholson · Aug 19, 2011

Correct!
Same reason a tire valve will get cold when the air rushes out.
Same reason a spray can valve gets cold.
Same reason (but in reverse) when a hand tire pump gets hot at the bottom.
Cars and modern vehicles have heat stoves or intake heaters to eliminate carb freezing. It can get to the point that internal ice builds up acting like a choke plate. it will run way rich, and stall. The change happened about the mid 60s for many cars. Some tractors have had a stove system hooked between the Muffler surround, and the intake to prevent icing. Jim

Victory! (carb/governor problems)

Sean0918

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JRSutton

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FC Andy

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Jason the Red

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Owen Aaland

Well-known Member

Janicholson

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