Carburetor Freezing Up

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Model T Ford Forum: Forum 2014: Carburetor Freezing Up
Top of pagePrevious messageNext messageBottom of page Link to this message  By Patrick Mulrooney, Webster, NY on Monday, July 21, 2014 - 08:50 pm:

Evening everyone,

I have researched this subject but did not find any conclusive answers. Of course, it could be my searching skills are lacking. At any rate, my friends 1915 Touring has a Kingston carb. All was well in the universe until today. We were on a "few" mile jaunt and his engine began sputtering and had a loss of power. When we got back to the house, we noticed the carb had a significant amount of "frost/ice" build up. Is there a common cause for this? He does not have a "hot air pipe" installed. This has not been a problem until today. No change in fuel/oil, etc...

As always...Thank you !


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Monday, July 21, 2014 - 08:57 pm:

Needs a hot air pipe. This will bring the air intake past the exhaust manifold heating the air.

Icing depends on the air temperature and the humidity. The more humid the colder the carburetor will become.

Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank Harris from Long Beach & Big Bear on Monday, July 21, 2014 - 08:59 pm:

The intake air being compressed and then expanded in the carburetor causes it to lose 70 degrees f. So on a 90 degree day the air in the carburetor is 90 less 70 or 20 degrees. Warm air has more moisture or humidity than does cold air so the 20 degree air full of moisture simply freezes.


This is why airplanes with carburetors have hot air ducts allowing them to stop the carburetor form icing up. In an airplane with an icing carburetor you change the color of the seats. In a car you simply pull over to the side of the road and let the carburetor warm up. This is why Model T's have a heat muff to warm the incoming air.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Eckensviller on Monday, July 21, 2014 - 09:06 pm:

Well, this answers a question I was going to ask today about how icy a T's carb can get if I just left off that heat muff thingy.

Here's a little reading for you:
http://en.m.wikipedia.org/wiki/Carburetor_icing

...and a carb ice probability chart with convenient percent humidity reference lines, since non-aviation weather reports don't have a dew point on them:
http://www.kfackler.com/gtuf/carb_ice.html


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Eckensviller on Monday, July 21, 2014 - 09:08 pm:

Oh yeah, it's worth mentioning that the temperature inside the carburetor is dropped both by the Venturi effect AND the vaporization of the fuel. I don't know why Wikipedia doesn't go into the why of it all...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Patrick Mulrooney, Webster, NY on Monday, July 21, 2014 - 09:22 pm:

Thank you All for the incredibly fast responses! I have a hot air pipe on my car. We are going to switch it to his car and see what happens.

Thanks Again!

Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Thode Chehalis Washington on Monday, July 21, 2014 - 09:23 pm:

Here is an icing chart. Low power at moderate speed is most likely to show ice. The chart shows even at over 86F and 20% humidity that light icing is possible under low load. This is serious stuff when it comes to aircraft but not a big deal in a vehicle that travels on the surface or the earth.



Fixes include: adding a hot air pipe, run a little richer mix or running with throttle wide open. Wide open throttle causes less pressure drop and less temperature drop and less likely to form ice.

Jim


Top of pagePrevious messageNext messageBottom of page Link to this message  By John P Noonan on Monday, July 21, 2014 - 10:40 pm:

It amazes me that you could have an icing problem on a T in the midst of summer. A few weeks ago after letting my T warm up for a few minutes i noticed dripping coming from the bottom of the intake manifold at the carb connection, first thought was gas, but it was indeed just condensation, the manifold was cold to the touch. I know that with every modern car I've worked on, especially turbos, having a colder intake charge is what everybody yearns for because of the performance gains. Now i know the T motor is as basic as a motor could be, but wouldn't even it benefit from a colder denser air charge? I took the hot air tube off and installed an aftermarket cleaner, not sure if that was the right decision or not.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Garrison_Rice Minnesota on Monday, July 21, 2014 - 10:51 pm:

I think I'm right in assuming all updraft carburetors can be guilty of icing up. I also remember a few small block Chevies and some Ford flatheads having issues as well.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Eckensviller on Tuesday, July 22, 2014 - 01:34 am:

John, summer makes the ice worse. You can basically count on the inside of the carb always getting very cold but the warmer the ambient air is the more potential it has to hold moisture.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Tuesday, July 22, 2014 - 01:45 am:

The 150 and 165 HP Franklins in my old Bellanca got carb ice only at full throttle. And they used the same Marvel-Schebler carbs that were almost universal in light aircraft for 50 years or more.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John P Noonan on Tuesday, July 22, 2014 - 01:45 am:

Tim, I'm going to ditch the aftermarket cleaner and see if the factory hot air pipe really makes a difference.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Huson, Berthoud, Co. on Tuesday, July 22, 2014 - 07:19 am:

There seems to be a general agreement above that all carburetors suffer this mysterious icing. I am going to take the opposite side. I drive my Ts almost as much as anyone on this forum in every state in the West and most of the states in the East. I have 43,000 miles on my Center Door alone. many more miles on my other Ts and I have never known of this mysterious icing??? Note I have never used a hot air intake and NO ONE that I know in Colorado uses them. We had 217 Model Ts at the National Tour in Estes in 89. I was wagon boss and I did not know of a single mysterious icing.

NOTE: I am not saying that somewhere, sometime it didn't happen, just that I know of NO CASES of this mysterious icing.

picture


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Georgetown TX on Tuesday, July 22, 2014 - 07:23 am:

A Model T will always benefit from a colder air supply. You will notice an immediate increase in performance when the hot air pipe is removed.

Condensation forming on the outside (or inside) of the intake manifold is normal and expected. Any time air goes through a venturi temperature goes down as velocity goes up.

If you add a restrictive aftermarket air filter you will restrict velocity and hurt performance.

Kingston L series carburetors are notable for their poor performance compared to a Holley NH. I have not used one of them for any length of time for the simple reason you get less power from a Kingston L.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Tuesday, July 22, 2014 - 07:35 am:

I've had it happen WITH the hot air pipe. This was on my TT. We had just driven 15 miles to the next town at highway speed (25mph :-)). When we got to town, we had to stop for a few minutes and wait to turn left into the show parking lot. When we were allowed to move again, the truck was running kinda rough. When I opened the hood for the car show, the lower end of the manifold was totally white. No doubt the inside was as bad or worse.

If you can get by without one, and originality is not your thing, then by all means run without it. No doubt there is a little extra HP to be had in doing so. I've never run without the hot air pipe other than when we first got my wife's '18 Touring. It did not have one, but I had a spare, so I put it on not long after we got the car.

Again, my icing episode was WITH the hot air pipe, so I'm not real eager to run without one.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Garrison_Rice Minnesota on Tuesday, July 22, 2014 - 07:45 am:

Dave, it's not really mysterious. It happens a lot. Perhaps the environment you drive in isn't conducive to having carburetors ice up. And the worst problems I've had with icing up happened with my 1930 Farmall Regular. Many of the old guys use to cut out a flap of inner tube and hang it over the carburetors. The Venturi effect and richness of the fuel/air mixture causes the icing. Altitude and temperature can be protecting you from icing up. I'm just guessing but for those of us that live with high dew points in the lower elevations have a greater opportunity. I always wondered how a refrigerator that operates on gas and has to have a flame to cause the Venturi effect can operate. It's counter- intuitive to think heat causes cold but the Venturi effect allows it to happen.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ivan Warrington on Tuesday, July 22, 2014 - 08:53 am:

Hmmm, our race car engines that use straight alcohol would form a solid layer of ice on the intake manifold. Could the alcohol in todays gas be causing frosty intakes??


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ivan Warrington on Tuesday, July 22, 2014 - 09:09 am:

Hmmm, our race car engines that use straight alcohol would form a solid layer of ice on the intake manifold. Could the alcohol in todays gas be causing frosty intakes??


Top of pagePrevious messageNext messageBottom of page Link to this message  By Patrick Mulrooney, Webster, NY on Tuesday, July 22, 2014 - 09:34 am:

Good morning Ivan,

An excellent thought about the ethanol, but we run non-ethanol in the "T"s. It is odd as he has been driving it the past several days with no issue other than wheel related, but that is a story for another time :-) . The freezing just happened yesterday while we were on a 5 mile hot lap around the neighborhood. Weather was nice (upper 70 to lower 80). It was slightly humid but not overwhelming.

Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Pat Kelly on Tuesday, July 22, 2014 - 11:07 am:

My '26 is running a NH with a foam air cleaner. I only get icing when the humidity is very high. The other day I was in the shop tinkering and running the motor and it was raining out at 75*. I had quite a bit of icing. It's usually not a problem even in winter. I carry a hot air pipe in the parts box in the trunk just in case when on the road. I run to many dirt roads not to run a air cleaner.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Tuesday, July 22, 2014 - 11:34 am:

I love it when this discussion comes 'round every 6-12 months. Folks who have never experienced frosty intakes (not just sweat) will tell you it CAN'T HAPPEN. I'm told that bees can't fly, either, but here in humid Florida, my lying eyes have seen and experienced both. And like bees, in FL, frosty intakes usually can be seen in the summer...but unlike bees, it isn't that common.
A hot air pipe relegated ice and sweating to just a memory, and since I neither drive nor desire to drive faster than 35 MPH, any loss of performance is pretty much invisible to me. 20 MPG and buttery-smooth running is good enough for me.


Top of pagePrevious messageNext messageBottom of page Link to this message  By G.R.Cheshire on Tuesday, July 22, 2014 - 11:57 am:

First time I saw the ice form on mine was in June I pulled into the 4th Saturday Cruise-in in Springfield And was opening my hood the guy beside me was talking about the cold air system he just put on his Dodge Demon. I saw the ice on my intake and had to ask him YEAH but does yours get this cold? His response was how do you get that?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Tuesday, July 22, 2014 - 12:17 pm:

Scott 35 mph? 35?!? I say, I say that's so slow you might as well be goin' backwards boy! LOL, now lookee here, you ain't even really movin' yet until you get up past 50.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Tuesday, July 22, 2014 - 01:01 pm:

Seth

you made me laugh out loud! I have a mental image of Foghorn Leghorn reading me the riot act!

I am duly chastened sir!

Oh, and just to be clear, hot air pipes do not make bees fly...that's another matter altogether.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Schedler, Sacramento on Tuesday, July 22, 2014 - 01:03 pm:

The cool air for comfort on the RC-121 was produced with ventures, but we had so much electronics (with tubes) on board that it didn't always do the job. The pilots usually were comfortable though.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Tuesday, July 22, 2014 - 01:36 pm:

Haha, great! I'm glad you got it and that it made you laugh. =) He's one of my favorite cartoon characters.

Nothin' wrong with going slow! I prefer to poke along myself. I just like being ABLE to go fast when I want to. My granddad always bragged that Eliza would outrun anybody's Model A. HAHA! He may have been exaggerating a bit but she'll sure enough dust most T's, except for maybe Fast Frank and anybody with an OHV.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erich Bruckner, Vancouver, WA on Tuesday, July 22, 2014 - 02:06 pm:

Mine gets ice on it, but never has any negative performance issues, no preheat ever.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Warren Henderson on Tuesday, July 22, 2014 - 02:35 pm:

Patrick, it is a lot more humid back here in the east, than out west and that contributes to your problem. I do not use a hot air pipe either and have had no trouble so far (hope I didn't put my big foot in my mouth again). There was one time however that I saw frost on my carburetor and that was back in June 19, 2011. A warm humid day, I had driven over to Bow, New Hampshire, about a ten mile trip. I was going to a car show at the Bow Bog Meeting House, so when I got there I opened the hood and the carburetor was completely covered with frost. Only time that I have ever noticed any.

Happy motoring,

Warren

Cold weather works great for Sambuca.


Top of pagePrevious messageNext messageBottom of page Link to this message  By keith g barrier on Tuesday, July 22, 2014 - 02:52 pm:

I wonder why Ford put a hot air pipe on them? I figure there was a reason so I run one all the time and have never had an issue with frosting. I don't think running without one would gain any appreciable hp either as it is not really as restrictive as one might think, MWO. KGB


Top of pagePrevious messageNext messageBottom of page Link to this message  By Patrick Mulrooney, Webster, NY on Tuesday, July 22, 2014 - 03:20 pm:

Great info and stories! Seth, I almost choked on iced tea after reading your tut tut to Scott! :-)

I honestly did not look at the intake but the top of the Kingston carb was iced over and there was a puddle of water below the carb. We checked the radiator and hoses just to make sure the water below was not from a leaky connection. I am curious though... if the water from the ice melting on the top of the carb made it into the inlet of the carb while the car was running, that would make the engine burp and sputter would it not?

Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Tuesday, July 22, 2014 - 03:32 pm:

Keith,

It's not the restriction so much as the warmer air is less dense than colder air. HP is directly proportional to the amount of air you can feed into an engine. Hence the reason for turbochargers and superchargers and cold air pipes on high performance vehicles.


Top of pagePrevious messageNext messageBottom of page Link to this message  By tillie the 15 on Tuesday, July 22, 2014 - 04:08 pm:

hey all--im the poor poor guy with the 15 that has the stumble fumbles. Prior to my issues last night the car was performing very well for the past couple weeks. i am going to run it again tonight--its hot here today to see if i can recreate it. A little more info- carb was recently rebuilt and performing very well. The motor was rebuilt recently and new radiator with no leaks.I also have checked wiring to be sure there are no pesky gremlins jumping around. Its acting like a fuel issue.Once up to speed she was running well but any hill that required power there was none. Starting from a stand still was a killer with the popping through the carb would be the worse no matter how i adjusted the carb. I checked fuel flow and its good out of the potato.Checked the vent hole in the new gas tank and its clear. I run fresh no E fuel ( stupid E fuel- hate that crap). I will also be trying the hot air pipe but am not convinced thats the issue- i have seen many cars with and without one but i also understand that not every motor/car/ ect are the same. i just started it up with the same results even without icing- i did drain fuel out the carb prior in case there is water.I did ground each plug to be sure i did not have an ignition issue. Each grounding cause a reaction in motor speed. Thanks for the responses---keep them coming!! and ill keep this updated-----PS Patrick.....cold beer and your guy is back.....


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jeff Schreier on Tuesday, July 22, 2014 - 10:47 pm:

Popping through the carb...sounds like an intake leak


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jeff Schreier on Tuesday, July 22, 2014 - 10:52 pm:

I should have been more specific...intake MANIFOLD leak. Try new manifold gaskets, I bet that will fix your problem.


Top of pagePrevious messageNext messageBottom of page Link to this message  By tillie the 15 on Wednesday, July 23, 2014 - 04:57 pm:

ding ding ding winner winner chicken dinner. air leak intake manifold on the back end. i am using one piece gasket because exhaust manifold is a little warped. i have it better but there is still a small leak causing motor fluctuation when i spray some accelerate around the intake by the gasket . ill have to move it around a little more. Thanks jeff and Mr Richie!!!!!!!!!!

Marty


Top of pagePrevious messageNext messageBottom of page Link to this message  By James Michael Rogers on Thursday, July 24, 2014 - 07:29 am:

I have had an intake to frost up in several types of cars and flatheads are not exclusive to the problem. I have had early VW engines that frosted just like a Model T and A. I do find it to be a non existant problem when using an aluminum intake.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Eckensviller on Thursday, July 24, 2014 - 01:33 pm:

I suspect the aluminum intake warms up with engine heat, which then warms the carb up. As long as the carb itself stays above freezing I would imagine ice can't build up within it.

I occasionally fly one of the first Cubs built (by Taylor, back when Piper was just an investor) and it gets by on a carb kept warm by engine heat. As long as the oil is up to operating temperature and there's a thermally conductive gasket between the carb and manifold, I trust carb ice won't be an issue.


Top of pagePrevious messageNext messageBottom of page Link to this message  By samuel pine on Thursday, July 24, 2014 - 05:13 pm:

Being curious with this topic ambiant temp is 78*
so I took a ride and felt it. It was as cold as
a water bottle from the fridg, and It has a hot
air pipe. I think the real test is, when its about
38* and big wet snow flakes. I'll bet ice will
form.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Warren Henderson on Friday, July 25, 2014 - 06:39 am:

Thank you Patrick, I think in rereading your post, it has helped clear up a problem I have been experiencing the past two summers, mainly the lack of Sambuca's usual power. Now I'm beginning to see the value of installing a heat pipe. I have a very good friend who has often told me that he has "a burnt-out refrigerator light bulb, that is brighter than me". He never has explained, nor have I ever bothered to ask what he meant by that.

Happy motoring,

Warren

PS: Samuel, being your northern neighbor, I respectfully believe that it is the humidity and not the temperature that causes the problem. I have enjoyed many, many winter outings with my T.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Friday, July 25, 2014 - 06:50 am:

HAHA Warren, I just spit some of my drink out on my desk. Burnt-out fridge bulb, that's good.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Warren Henderson on Friday, July 25, 2014 - 07:19 am:

Sorry about that Seth.

Happy motoring,

Warren


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug Money - Braidwood, IL on Saturday, July 26, 2014 - 12:40 am:

I've had my T for 9 years. In that 9 years it has iced up to cause problems only twice. I don't run a hot air pipe. It can ice up but twice in 9 years, I am not going to worry about it.


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