MTFCA Forum

A friend says his Model T never had a Hot Air Pipe, Part Number 4582, so he knows it must not need one.

My opinion is that Henry Ford would never put that part on, if it was not required.

There are usually three different opinions about every part of a Model T, am I wrong on the pipe requirement?

Well, it depends on the type of gasoline you use and the weather.

If you use a heaver gasoline with kerosene blend then the Hot Air Pipe is necessary to help vapourize the fuel.

If you follow the literature after 1917, the hot air pipe is a necessity for winter and cool weather. For summer or hot weather it can be removed.

Also in cold weather it acts has a deicing device.

I had my T choke and stop running of a cool moist morning without the hot air pipe. There was visible white frost on the outside and most likely on the inside of the intake manifold. We stopped while it thawed out only to have it repeat the problem several times. The afternoon was warmer and we didn't have that problem. That is the reason they were installed. Some folks like to keep it stored away and installed when the weather requires it. The car may run cooler without it. I just leave it in place now.
Rich

I have never had need of one in sunny South Australia. It is rare to ever see one at Australian swap meets.

Allan from down under.

I have tried it both ways and my ‘26 coupe operates much better with the hot air pipe. I would assume that the injection of hot air aids in the atomization and combustion of the gasoline. Jim Patrick

My friend limped his '25 roadster to my house and complained the car ran terrible. I told him to go look at his carb and intake. He reported finding it "all wet."
Some model t performance officiando earlier that week told my friend removing the pipe would " give him more power."
Instead the car became an ice maker in 80f and 65% humidity.
I ended up giving him the one off my '26 so we could go touring around and so he could get home later. He lives 1300 ft higher than my place too.
I've experienced carburetor icing in Cessna's a half dozen times. No fun in the air or on the ground... pipe or no pipe?
I vote pipe..... But to each his own. I respect that.

My '17 roadster has a Wilmo manifold and a hot air pipe so it's like the guy who wears suspenders and a belt.

This seems to one one of those things where different people with different cars in different places experience different results.

Because I drive on country roads a lot, I run an air filter, and therefore no pipe. So far it hasn't given me any trouble.

Dry air will not normally cause issues even when it's fairly cool, when using modern gasoline. Air which contains moisture can cause moisture or frost to accumulate in the carburetor and manifold in cool damp weather. This is true of any carbureted vehicle I've ever owned that lacks some type of manifold heating arrangment,and many later vehicles have both manifold heat (hot spot) and some method of heating the intake air. A Model T without the heat pipe installed lacks any kind of manifold heat and any method of heating intake air until the engine begins to circulate hot water. Under some conditions, the heat from the radiator may not be enough to prevent problems. When the engine is operating at light throttle, the carburetor and lower intake manifold are cooled by expansion of air passing through the throttle restriction and also by rapid evaporation of gasoline. The throttle plate area of the carburetor and the lower portion of the intake manifold can quickly become cold enough to freeze moisture in the air and cause frost deposits inside the carburetor throat, and the very cold surfaces inhibit gasoline vaporization. The outside of the lower intake maqnifold may become white with frost. I have heard or read that ethanol gas will prevent carburetor icing. What I have found with a 1972 Ford 360 2V with no operating manifold heat valve or air intake heat is that the carburetor will "freeze up" in cool damp weather running ethanol gas. The problem goes away once the thermostat opens and warms the air under the hood.

I run my hot air pipe in the winter and an air filter the rest of the year. I do get condensation on the carb body during drives with the air filter, but so far no ice or other ill effects.

In a airplane with a carb you have selectable carburetor heat. In 5000 + hours of flying I have very seldom experienced carb icing. When you apply carb heat the RPM drops and the engine loses a small amount of power. The warm air produces a richer mixture.

Back in the day I believe the hot air pipe served mostly to help vaporize the poorer quality fuel of the day. I used to run a hot air pipe but replaced it with an air filter. The result? Never had an engine problem due to icing but did see an increase if fuel mileage. This is in Michigan with temps ranging from 45 to 95 degrees. I carry the heat pipe under my back seat....just in case.

I recently replaced my Holley G with a NH with Scott's full-flow valve. I have yet to drive it (maybe today.) I'll start off with the filter installed and see what happens.

The warm air helps vaporize the fuel and prevents icing.

Cool air makes a denser charge.

With the correct combination a bit more power is possible.

Suggest that some invest is a book - The Model T Ford Owner, Fahnestock.

Information on why there is a hot air stove, why gasoline is different, why a bit of water injection improve performance, which carburetor is best for performance and more.

As for cold air induction...still popular to day.

I'm a believer in delivering filtered air to an engine. I use the spring loaded foam filter available from vendors. I live in humid Alabama. I've seen condensation on the outside of the manifold, but run with no issues. With the filter against the hogs head it may pick up some heat, but I'm not using nor do I plan on using a hot air pipe.