# Why no air filters?



## ChrisJ (Nov 27, 2014)

So this may be a dumb question but, why have I never seen a snowblower with an air filter?

My best guess is if snow gets on the filter it'll really suck, but what are the chances of that if it's in a decent housing?


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## sscotsman (Dec 8, 2010)

No kicked-up dust to worry about in the winter..
snowblowers simply dont need them.

Scot


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## ChrisJ (Nov 27, 2014)

sscotsman said:


> No kicked-up dust to worry about in the winter..
> snowblowers simply dont need them.
> 
> Scot


Hi Scot,
I was hoping you would reply. Thanks!


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## Kenny kustom (Nov 25, 2014)

Mine has one.


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## 43128 (Feb 14, 2014)

the paper/foam would get clogged with water/snow and freeze up, causing the engine to choke itself and run rich or not run at all. also there is no dust


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## Big Ed (Feb 10, 2013)

Mine has one also.


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## ChrisJ (Nov 27, 2014)

Kenny and Ed, did they come that way or did you add one?

Do you have pictures?


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## Ariens1976 (Jan 1, 2013)

Hondas have one, no? Or is that just an empty filter housing?


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## ChrisJ (Nov 27, 2014)

Ariens1976 said:


> Hondas have one, no? Or is that just an empty filter housing?


My neighbors HSS622 it's just an empty housing.


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## Big Ed (Feb 10, 2013)

ChrisJ said:


> Kenny and Ed, did they come that way or did you add one?
> 
> Do you have pictures?


Came with it, though it is not your normal snowblower.
It is a classic machine. 

It is in here, http://www.snowblowerforum.com/forum/snowbird-snowblowers/29233-vintage-1963-snowbird.html


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## Sblg43 (Jan 18, 2014)

The Honda that I fixed had an empty housing.

Sometimes at work (I work at a hardware store) when a customer is buying things to tune up his/her snow thrower such as oil, spark plug etc.. I will say "Don't forget the air filter" just to catch their reaction.

Most stop and think about what kind they need. Then I have pity and tell them the truth.


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## Kenny kustom (Nov 25, 2014)

It's a yamaha. 
It comes with.


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## Ryan (Dec 13, 2013)

The Honda 1032 at my church building also is an empty in that compartment.


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## whimsey (Oct 16, 2014)

I was under the impression that at least more recent snow blower engines came without air filters due to freezing and icing possibilities blocking the air flow.

Whimsey


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## Big Ed (Feb 10, 2013)

whimsey said:


> I was under the impression that at least more recent snow blower engines came without air filters due to freezing and icing possibilities blocking the air flow.
> 
> Whimsey


My guess is that years ago it was the norm to add a filter to ANY engine.
Then someone figured out that you wouldn't really pick up much dust in the winter.

But what about snow dust? 
I would think some kind of cover, even without a filter, would be good to have anyway?


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## Ariens1976 (Jan 1, 2013)

Most of the machine I've seen has some sort of heater box over the carb... in my experience, it takes a good wind and a great amount of snow before a machine "ingest" snow in the carb.


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## ClaudeK (Jan 4, 2015)

I always thought the colder air is better for combustion. If not then why there are intercoolers. Besides my suby runs far better in cold then in hot weather. And I would not be worrying about tiny bit of snow dust getting into carb. Saw a video where guy sprayed a tiny bit of water mist into his car's intake with the engine running to clean combustion chamber. Dunno if it works, guess it does


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## ChrisJ (Nov 27, 2014)

ClaudeK said:


> I always thought the colder air is better for combustion. If not then why there are intercoolers. Besides my suby runs far better in cold then in hot weather. And I would not be worrying about tiny bit of snow dust getting into carb. Saw a video where guy sprayed a tiny bit of water mist into his car's intake with the engine running to clean combustion chamber. Dunno if it works, guess it does


It's far, far more complicated than "cold air is better".

Early cars had intake manifolds bolted right to the exhaust manifold to try and heat it as well as the carburetor. Both the Ford Model T and Model A are like this. Holley even made a carb called the vaporizor that boiled fuel intentionally.


Now, I may screw this up but I'm going to do my best.

There are several issues one of which is Fuel Atomization. I believe warmer air does this better and I think it was the primary reason early cars had burning hot intakes. Also, even in the 1980s and 1990s many V6 and V8 engines ran coolant through the intake to heat it. They even had a valve that would shut and force exhaust through the intake to heat it rapidly, though I only saw this on mid to late 1980s carbed cars. Don't confuse this with EGR which is used to cool combustion temperatures, it's completely different.

Also, I believe you can run leaner mixtures with warmer air. I was told this is why starting in the 1970s many cars had "heat stoves" that pulled air from one of the exhaust manifolds into the air cleaner controlled via a thermal controlled damper.

Not to mention in our situation it likely allows the engine to run a little warmer especially in extreme cold.

Turbocharged engines use intercoolers to bring the air temperature down because it goes up when you compress it. 

Again, on a performance machine and especially one that is fuel injected cooler air temperatures mean more power because the air is more dense.

But, it's not a one size fits all.


Just as an example, here is a stock Ford Model A setup. The intake has a large flange that bolts to a machined flange on the exhaust manifold to transfer heat. The cast iron carburetor gets so hot you can't even touch it and this was all 100% intentional. Mainly because those carbs were nothing like a good one from the 1950s-60s, but I gotta admit it's better than whats on a Tecumseh or Honda small engine.


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## dbert (Aug 25, 2013)

The heat is all about carb icing.
It's especially a big deal on naturally aspirated airplane engines.
Carburetor heat - Wikipedia, the free encyclopedia
It takes the right combination of temperature and moisture, but as the air pressure drops going through the venturi of the carb there is a temperature drop as well.


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## ChrisJ (Nov 27, 2014)

dbert said:


> The heat is all about carb icing.
> It's especially a big deal on naturally aspirated airplane engines.
> Carburetor heat - Wikipedia, the free encyclopedia
> It takes the right combination of temperature and moisture, but as the air pressure drops going through the venturi of the carb there is a temperature drop as well.



I could believe that if all of the examples I gave produced heat which effected the carb.

The heated intake manifolds from the 1950s-1990s did not.

I've heard of it in airplanes, but as far as I know it's pretty rare outside of that.

Another example of what I was talking about : http://www.langdonsstovebolt.com/tech/why-you-need-to-heat-your-intake-manifold/


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## Normex (Feb 21, 2014)

dbert said:


> The heat is all about carb icing.
> It's especially a big deal on naturally aspirated airplane engines.
> Carburetor heat - Wikipedia, the free encyclopedia
> It takes the right combination of temperature and moisture, but as the air pressure drops going through the venturi of the carb there is a temperature drop as well.


 Tell me about carb icing as I have a private pilot license (don't fly anymore) and once on my return leg the engine had a slight rpm drop so I pulled on the carb heat and as expected the engine ran even rougher which is expected when the ice melts in the venturi. Just a small scare but alive to tell about it and the outside temp was in the forties.


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## db9938 (Nov 17, 2013)

I can remember nearly every N/A late '60's- early '70's car I have worked on, had a manifold duct up to the horn of the air cleaner. It was usually the one thing that always got mangled when you took the breather completely off. It also was attached to a thermostatically controlled vacuum line, that would open and close it.


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## ChrisJ (Nov 27, 2014)

db9938 said:


> I can remember nearly every N/A late '60's- early '70's car I have worked on, had a manifold duct up to the horn of the air cleaner. It was usually the one thing that always got mangled when you took the breather completely off. It also was attached to a thermostatically controlled vacuum line, that would open and close it.



They continued to use this into the 1990s. My 1992 Chevy C2500 truck had one even with throttle body injection.

i've attached a picture of it. Though, mine wasn't mangled even after 225,000 miles. 

Like I said, as far as I know these were used to provide warmer air to allow a leaner mixture. I never heard any different and it's certainly why it's an EPA violation in the US to tamper with it.


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## [email protected] (Nov 21, 2011)

Honda snow blowers don't have air filters.

To keep costs down, the air cleaner _housing_ used on many Honda engines is still fitted to a Honda snow blower engine, there are just no filters inside it. 

The housing is still there because it is structurally part of the carburetor mounting design.


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## Ryan (Dec 13, 2013)

Just a liiiiiiitle bit rusty there on that air filter housing. But it got ya to that millage  Sucks when the A/C compressor fails though, that is a very expensive repair


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## ChrisJ (Nov 27, 2014)

Ryan said:


> Just a liiiiiiitle bit rusty there on that air filter housing. But it got ya to that millage  Sucks when the A/C compressor fails though, that is a very expensive repair


Ah, you noticed the A/C compressor.

I took that picture right after rebuilding the A/C system.
Converted it to R134A, new compressor, new condenser, new barrier type hoses, new pressure switch (lower than R12), new accumulator and new severe duty fan clutch.

I was able to get 36F vent temperatures on a 95F day sitting in traffic. 

I was a bit nervous though, I had frost going right to the back of the compressor a few times.


R12 systems converted to R134A usually suck because they are done wrong. When done right, they can work fine.


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## Kiss4aFrog (Nov 3, 2013)

ChrisJ said:


> Like I said, as far as I know these were used to provide warmer air to allow a leaner mixture. I never heard any different and it's certainly why it's an EPA violation in the US to tamper with it.


Those pre heater hoses don't do anything to allow leaner mixtures. The reason they have controls is to close them off once the engine warms up a little. They were only in use during a cold start and they had controls to seal them up so you're sucking in cool air after the engine warms up enough to give heat to the throttle body to prevent icing. It's just an icing issue and a lot of throttle body cars had coolant going to the TB to prevent icing.


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## ChrisJ (Nov 27, 2014)

Kiss4aFrog said:


> Those pre heater hoses don't do anything to allow leaner mixtures. The reason they have controls is to close them off once the engine warms up a little. They were only in use during a cold start and they had controls to seal them up so you're sucking in cool air after the engine warms up enough to give heat to the throttle body to prevent icing. It's just an icing issue and a lot of throttle body cars had coolant going to the TB to prevent icing.



Yes, many throttle bodies on modern cars are heated to prevent icing.
However, I believe this is fairly rare and a lot have eliminated the practice. My 2006 vehicles had it, my 2012 do not.

Back to heated air intakes and manifolds.

Early fuel evaporator - Wikipedia, the free encyclopedia

Warm air intake - Wikipedia, the free encyclopedia



". The purpose of the EFE heater is to aid with vaporization of fuel in cold conditions, as well as to reduce exhaust emissions by running for about two minutes to allow for leaner choke calibrations."

I may be wrong about it allowing for leaner mixtures during normal operation, but it's still primarily for leaner fuel mixtures when the engine is cold.
Ever see such a thing on a pre-1970s car? There's a reason and it's not for carb icing.


A recent patent.
https://www.google.com/patents/US20...&sa=X&ei=ml65VLejGcmlNomRgsgJ&ved=0CB0Q6AEwAA

"The purpose of Intake Air Pre-Heater Assembly is to vaporize more of the gasoline going into the combustion cylinders of the common automotive gasoline multiple fuel injector engine."

And, the nail in the coffin of the dead horse.
"It is a known fact that intake air pre-heaters preform a very useful purpose because mechanical intake air pre-heaters have been installed on millions of other vehicle gasoline engines and are known as “Early Fuel Evaporation” systems. This system channels warm air from one of the exhaust manifolds into the air intake duct of the air filter until the engine warms up and then the warm air is shut off by a thermal vacuum valve or a thermal coiled spring."

EFE systems.
http://tech.oldsgmail.com/emis_EFE.php

My opinion stands. The heated intake on the Tecumseh is to aid in fuel vaporization and possibly, to help with carb icing.
Yes, the ones on older cars were only used until the engine (and it's heated intake) warmed up but the Tecumseh doesn't have a heated intake and has a very cheesy carburetor. Chances are such a setup works fine in warmer weather but not so fine when it's cold out.

Not to mention, it would allow for faster warmups just as with a car.


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