Carb Icing

[TimberXX]

I've heard about carb icing. Has anyone heard of icing issues with the Honda gx engines? Is there anyway to reduce the chances. I've read about carb heaters in planes, but nothing for small engines.

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[PILOON]

Most small i/c engines used on snow blowers have a metal shield covering the carb that serve as an air pre heat area as well as generally do not have air filters. Besides snow would soon plug a filter.

On a friends NH tractor we had to rig a shield as snow would clog his filter when plowing.

Old VW beetles also could ice up the carbs. Happened to me but then as a pilot I figured that out promptly.

 

[Baby Grand]

As the air enters the venturi, it speeds up, causing it's pressure (and temperature) to drop.
This sudden reduction in temperature causes some of the moisture in the air to condense on the carb.
If the carb's venture surface is cold enough, this condensate forms ice - and power starts to drop off, due to the restriction.
If you can raise the temperature of the air before it gets to the carb's venturi, you can reduce or eliminate icing.
Another way you can reduce or eliminate icing is to heat the carb itself.
On a small I/c engine, preheating the carb is going to be very difficult.
Preheating the intake air would also be a challenge, due to the short length of the exhaust and intake.
Maybe you can find a way to route the air going to the intake so it first passes over the exhaust?

 

[Egon]

Remember the older engines with a heat riser?

 

[PILOON]

Referring to snow blower engine installations, a simple piece if tin added to the offside of the carburetor thus limiting air intake from the area near the warm engine head and cylinder body should be adequate preheat.
A few bends and creases in the tin shield could direct air intake passages as well. Slits are generally needed for choke and throttle controls.

Most snow blower application shields have the bottom folded such as to practically deny bottom air intake and forcing all intake to flow from over and around the cylinder head and exhaust outlet. Most flywheels serve as a fan as well and blow air over the cylinder head and thus provide warmed air to the intake. Simple but it works and also prevents snow ingestion as it then is somewhat pressurized as well as being warm.
Not enough to be turbocharged however LOL.

 

[WilliamTO-35]

Carburetor icing in automobiles is actually the worst in temperatures slightly warmer than freezing . Anti-icing additives are added to gasolines to reduce the problem. With a snowblower, however, the situation is somewhat different . If a mist of snow is actually reaching the air intake , some shields may help, as mentioned in posts above. I recall my riding mower engine in summer suffered from vapor lock, using gasoline blended for the previous winter. The volatile gasoline was boiling in the float chamber. To combat this, I added two additional layers of paper type gasket material between the carburetor and the engine block, I insulated the fuel line , and I installed an aluminum shield between the block and the carburetor. To combat icing, doing just the opposite , in every case, may solve the problem. Remove the carburetor gasket , and use three layers of aluminum foil for a gasket.
Add a length of copper or steel fuel line , and route it close to engine heat. Use a shield to keep engine heat in the area of the carburetor. Run on winter blend gasoline, since it may contain more anti-icing additive. Find a gasoline additive that claims to reduce carburetor icing . (It may just be ethanol, and 10% ethanol is already enough.) Don't add methanol to your fuel, unless your owner's manual says it's ok. Methanol is nasty stuff.

 

[tcartwri]

Our Honda generators have electrical carb heaters. I wouldn't be surprised if your snow blower does as well.

 

[Dave M7040]

I had a problem with my Honda EM 3500 generator in cold weather. The crankcase vent system froze up and oil came out everywhere. It happened in the middle of the night . Thank goodness for its low oil sensor or the engine would be toast. Rather than have the hose for the crankcase vent continue to go into the carb intake, I just had a short piece of hose dripping unto the ground. Power was out for 10 days and the generator saw a lot of use.
Dave M7040