Carb Sweating

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Model T Ford Forum: Forum 2017: Carb Sweating
Top of pagePrevious messageNext messageBottom of page Link to this message  By Burt Koenig on Friday, March 31, 2017 - 09:57 pm:

24 carb and intake manifold sweating heavily COLD. Can't find any restrictions.
Engine running rough when try to accelerate.
Cylinder 1 no real change when grounded.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Friday, March 31, 2017 - 10:06 pm:

Burt, installing the hot air pipe on our car cured this exact problem


Top of pagePrevious messageNext messageBottom of page Link to this message  By Pat Kelly Montana on Friday, March 31, 2017 - 10:07 pm:

Sounds like icing. Are you running a hot air pipe?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Friday, March 31, 2017 - 10:10 pm:

This is why a heat stove/pipe is used. This can happen even on warm days if the out side air is moist. The sweating is not from a blockage. The Model T intake does not have a heat stove or hot spot to heat/dry the incoming air. At idle you might even see frost forming on the outside of the intake.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange - Hillsboro, MO on Friday, March 31, 2017 - 10:12 pm:

Once you get the hot air pipe installed, pull and clean the #1 spark plug, it's probably fouled. If #1 still doesn't fire, swap coils to see if the misfire follows the coil or stays at #1.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Burt Koenig on Friday, March 31, 2017 - 10:40 pm:

One thing we have in Houston is moist air.
Around 100% humidity.
I will need to look up a hot air pipe.
I have never seen one.
Thanks for the info guys.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Friday, March 31, 2017 - 10:45 pm:

Just google "mtfca; hot air pipe" you will see plenty. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Noonan - Norton, MA. on Friday, March 31, 2017 - 10:49 pm:

With plenty of differing opinions,...and maybe some colorful language. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Friday, March 31, 2017 - 10:54 pm:

:-) that's for sure!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Saturday, April 01, 2017 - 08:21 am:

yes, you will, so let me start

The sweating you saw was actually your imagination.
The fouled plug is really somehow your fault.
The improved performance others have found by using a hot air pipe in high humidity areas is their imagination.
A hot air pipe will decrease performance - it will feel like your car has only 20 horsepower.

Oh, I feel so much better LOL!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Wrenn-Monroeville OH on Saturday, April 01, 2017 - 09:16 am:

Burt, yes the humidity is a huge part of the equation. Have had that happen up here in wonderful N. Ohio on a damp spring evening. The intake manifold was coated in ice, engine a bit rough but not bad and once it got warmed up good, settled out. That said, you can get these pipes from any vendor. They're not expensive.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange - Hillsboro, MO on Saturday, April 01, 2017 - 09:24 am:

You can get them from the vendors, but they don't look or fit as well as the originals. There are variations in the pipe by year, so do some research and be sure to get the correct OEM pipe for your year car.

Side-by-side comparison of an OEM 1924 vs. reproduction hot air pipe:

pic1 pic2


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill Harper - Keene, NH on Saturday, April 01, 2017 - 11:20 am:

Hi Burt,

As mentioned above, carburettor sweating and/or icing IS REAL and not fake news. It's occurrence is dependant upon two factors: certain ambient weather conditions AND the absence of the hot air pipe.

Now, some folks here (many?) will claim that the hot air pipe is not needed and can actually rob the engine of some efficiency and power especially during hot weather. There may be some truth to that proposition.

I have experienced carb icing on several occasions and always when the hot air pipe was not installed. The engines ran poorly: spitting and coughing, just lousey. Added the hot air pipe and all was fine. Works for me, your milage may vary.

Here is a carb and intake manifold with icing:


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange - Hillsboro, MO on Saturday, April 01, 2017 - 11:38 am:

I removed my hot air pipe and ran an air filter last summer. I got condensation on the carb nearly every drive, but no icing. The car ran fine, actually seemed to have a little bit more power. I removed the filter and re-installed the hot air pipe in the fall. I plan to swap on the air filter again this summer. :-)

pic


Top of pagePrevious messageNext messageBottom of page Link to this message  By G.R.Cheshire on Saturday, April 01, 2017 - 11:45 am:

Come on you are making the Hot Rod guys jealous with your cold air intake! The Icing is being caused by humid air going through a venturi the air comes in through the carburetor then makes a 90 degree turn then slows down and expands this causes a drop in temperature therefore the Icing which freezes the water droplets inside the intake, Ice doesn't burn too good so you get poor performance. Simple as that. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Fred Dimock, Newfields NH, USA on Saturday, April 01, 2017 - 12:11 pm:

But but but in the old days we used water injection to keep the top of the pistons cool. Oldsmobile used it and we had 4 very small holes in the intake manifold to get water from the cooling system to the combustion chamber on our "stock" drag racing car. We were never caught.
It worked very well.

Just had to remember water only. No antifreeze!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Blake, Kansas City on Saturday, April 01, 2017 - 12:29 pm:

Sorry G.R. but I beg to differ. Air with high humidity means the water is already in vapor form. The chilling that takes place is due to the state change of the gasoline from a liquid to a vapor. That change of state absorbs a large amount of heat from the incoming air and chills the manifold. If you were driving in the desert, the manifold still gets cold, there's just not enough moisture in the air to condense any appreciable amount on the intake. The refrigerant in your home or modern car air conditioner undergoes this state change continuously when running. From liquid to vapor at the evaporator, where the air inside the passenger compartment gets chilled, And then back to the compressor where it gets pressurized and then goes to the condenser mounted in front of the radiator where it rejects the heat it took on and turns back into a liquid.

I will agree though that if there is icing on the outside there must be icing on the inside, and the water vapor in the air has undergone a change of state also, from a vapor to a liquid and then solid. Ice and I.C.E's (internal combustion engines ) are never a good combination.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Saturday, April 01, 2017 - 12:32 pm:

Have always run hot air stove pipes on the T's.

Here are the later styles, the early ones were cast iron or steel, just plain pipe with small flare, they don't have the shroud.

The Late '25-'27 are 'recessed' on the shroud for the newer U-joint carb rod, as it passes close to the shroud. Of course '27 Vaporizer carbs didn't have stove pipes.




Top of pagePrevious messageNext messageBottom of page Link to this message  By Anthonie Boer --- Klaaswaal NL on Saturday, April 01, 2017 - 12:38 pm:

Burt K ; About fouling # 1 spark plug ,read article in [ THE MODEL T FORD OWNER the BEST OF MURRAY FAHNESTOCK] page 303-305 that tells you all.
Toon


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Saturday, April 01, 2017 - 12:41 pm:

Many of the cars in the T era had some type of hot air pipe. Many of them had a door you could open in dryer weather ether on the pipe or the carb it self to allow unheated air to enter the carb. Even my 91 Dodge has a preheating pipe that has a vacuum/heat door to aid in startup. After the engine gets warm the door closes and engine heat is used.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Saturday, April 01, 2017 - 01:04 pm:

I've been in Houston and I worked up a sweat too! It's the humidity. It would probably be no problem unless it ices up. The evaporation of the fuel inside the manifold causes it to get cold and cold attracts vapor in the air which will condense back into water. You could try the hot air pipe. If the car runs better with it on leave it on, and if not, you can always remove it.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank Harris from Long Beach, CA on Sunday, April 02, 2017 - 08:25 pm:

Air going through the venturi of the carburetor drops 70 degrees in temperature. Warm air carries more moisture than cold air. So at 90 degrees the moist air going through your carburetor drops to 20 degrees and the water in the air freezes and turns to ice. At cooler temperatures it only gets cold and the moisture in the air collects as water on the outside of you intake system. At 110 degrees the air temperature drops to 40 degrees and doesn't ice up.

If you have ever flown in a small airplane with a carburetor on a hot day the pilot always turns on carburetor heat when he or she throttles back to descend for a landing and the vacuum goes off of the charts. If they don't turn on carburetor heat the engine will die when the carburetor ices up and the color of the seats will change in the airplane.


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