Frosty carb

Anonymous-0 · Nov 24, 2008

I have heard of people putting some type of heat shield on to keep carb from frosting. Any info or photo's of how this is accomplished would be greatly appreciated.

Bob M · Nov 24, 2008

Here's one: The "Pipe 'n Hot" home-made air inlet heater spotted on an H. Consists simple of a open bottom sheetmetal box hose clamped to the muffler. A short hose (not seen behind the box) gathers heated air from the top of the box and feeds it to the air cleaner inlet.

On my Super M I accomplish about the same thing by fully covering the radiator grille with a winter front (so the air coming off the fan is quite warm) then clamping a piece of sheetmetal to the frame rail to direct the warmed air back over the carb and air cleaner.

Andy Motteberg · Nov 24, 2008

Here is the one I use on my H. Made of a heater pipe and a flexible rubber hose. The pipe goes over the muffler. The pipe has a hole cut into it where the hose fits in and it is sealed with duct tape. The hose goes into the air cleaner inlet pipe. The heated air from the outside of the muffler goes into the air intake so the carb gets warm air. It works great. Here is a picture.

Andy

Fixer · Nov 24, 2008

I've had good luck adding a couple cans of heat to a tank of gas for this problem. It helps on my M. Bernie Steffen

Dave in CT · Nov 24, 2008

I made something similar to Andy's invention using a foot of male-ended 7" smokepipe, inserted into a 7" to 6" reducer, with a 2" 90 degree electrical conduit elbow coming out of the side. The reducer rests on the top of the main body of the muffler (I padded mine by riveting in some 1/2" fiberglass round stove gasket) and the elbow is clamped to a 2" hole in the stovepipe using a conduit clamp. The other end (female) of the elbow fits nicely over the intake of the air cleaner (with the pre-cleaner removed, obviously). I'll try to post a picture of it in the next couple of days.

Farmall wrangler · Nov 25, 2008

Just curious, As long as you don't get to a freezing condition what does the frost matter? I realize we aren't comparing apples to apples but we used to go to great lenghts to get as cold as possible air in to the intake on our race car. Cold air compresses more and produces more horsepower.

Bob M · Nov 25, 2008

You’re absolutely correct! The colder inlet air is the more dense it is. And more dense the inlet air the more power an engine will produce.

However when cold inlet air is also humid it causes ice to accumulate in the carb venturi and throttle plate area. The ice plugs carb ports and air bleeds at idle/low load. This changes carb calibration results (usually…) in an excessively rich condition which in turn causes engine stumbling, fouled plugs, etc.

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Note that all carbureted aircraft engines are equipped with a manual “carb heat” control. This is so the pilot can select heat (in exchange for slightly reduced power) when carb icing conditions exist.

Frosty carb

Anonymous-0

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Bob M

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Andy Motteberg

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Fixer

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Dave in CT

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Farmall wrangler

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Bob M

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