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LesH

Shroud Air Tube Question---

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LesH
On the Briggs and Kohler engines there is an air tube connected by a rubber hose (approx. 1 1/4 dia.)from the engine tin shroud to the outside area of the air cleaner (not the rubber tube from the valve area). What is the 1 1/4 inch dia tube for?? Preheated air?? If I close that tube up will it hurt anything?? As I dont have room for that tube in my newly transplanted engine in my tractor. Thanks.

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HubbardRA
If it is like the one that was on a 12 Hp Kohler that I had, it was taking the air from the engine fan and shooting that into the air cleaner. I guess it was sort of like ram air on a car. More consistent air flow, and possibly a little more throttle response from the engine. Should be no problem with eliminating that hose, as long as you block off the hole in the engine shroud to force the air to go on thru the engine and cool it. With it hooked to the air cleaner, the air would back up and still be forced thru the shroud. With an open hole, it will not, and you will lose quite a bit of cooling capability.

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2burning
That tube may help to keep the air filter cleaner for a longer time - big chunks aren't allowed in through the engine cooling screen, and the swirling of the cooling fan throws more dust out of the air before it gets to the tube and then the filter. Well, thats what I have read before anyway... :>

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MikeES
I was missing the tube on my 917 (no longer available from Kohler). I block off the opening in the fan shroud and left the opening in the air cleaner housing. This created too much negative in the carb area and sucked oil up from the breather (straving for air). I changed the air cleaner to the newer round style with more air filter area and do not have any issues. My 718 pulling tractor has this ram air tube also. When I disconnect the tube I must lean the carb down as the engine is not getting as much air and runs too rich. So my advice is if you do not use the tube you will need to open up more area to the air cleaner housing.

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HubbardRA
Mike, On my 12 Hp Kohler engine (when using it for pulling) I modified the air cleaner to use the much taller filter from some of the newer engines. I used a cheap, small, frying pan. Cut it to fit the carb, the fitted it to the back of the original air cleaner housing and cut out the old metal. This allowed me to install the much taller filter (nearly twice as tall). I then made an extension for the tube from the shroud to the air cleaner and re-installed it. It breathed very nicely then (especially after I hid the velocity stack inside the filter area). Who did that? Not me! Why that would be cheating! Well anyway, the tech inspectors never found it. LOL

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