MTFCA Forum

Hi all,
I was wondering about the carb heater pipe. I've seen engines with and without. Is it a necessity? I have one but haven't put it on. Am I missing a critical component? How does it affect performance? Thanks for the replies. John

It varies widely. Some T's run better, some do not. The largest determining factor seems to be the relative humidity in your area.
If your intake manifold @ the bend ices up & stays cold, The heat pipe will keep this from happening & she will run better.
If you are driving in a dry area there seems to be no improvement. There will be a little less performance from the restricted airflow.
The thing to do is try with it on & with it off. Go with what ever way performs best. Here on the coast, most T's run better with it on, but some it doesnt matter after the motor is up to temperature.

I run the factory hot air pipe in the winter, then remove it and run an air cleaner when the ambient temperature is consistently above 60 deg F.

I found my air cleaner on Ebay, it was originally designed for an old Clinton lawn tractor. I made an adaptor cone from sheet brass.

When running the air cleaner, I usually see condensation on the outside of the carb (a Kingston L4), but so far no ice.

Others will likely have opinions on the matter.

NY John T wrote: ↑

Wed Jul 12, 2023 4:38 pm

Hi all,
I was wondering about the carb heater pipe. I've seen engines with and without. Is it a necessity? I have one but haven't put it on. Am I missing a critical component? How does it affect performance? Thanks for the replies. John

Th intent of the carb heater pipe is to prevent the intake manifold from icing up. When the air fuel mixture expands inside the intake manifold expands it causes a temperature drop. In Today's World most reference's about it relate to aircraft but that really doesn't make any difference other than the changes in ambient temperature they experience in altitude changes .
Better explanation from others
-Cold air is more dense and therefore contains more Oxygen by volume so the mixture ratio can remain the same. Because the engine is cold at startup, and by extension, so is the air. Therefore there is more oxygen. So without enriching the mixture, the resultant mixture will to too lean to support combustion.
-Carburetor icing exists when the moisture inside an engine's carburetor drops below freezing and water vapor freezes onto the throttle valve and other internal surfaces of the carburetor. The build up of icing inside the carburetor causes a reduction of the fuel/air flow through the carburetor and into the engine.

NOTE the chart title says PROBABILITY which is in line with speedytinc & others indicate.

In New York state, you might try putting it on in October and taking it off in April or May.

I have a Wilmo manifold and a hot air pipe on my roadster - suspenders and a belt.

Thanks all. I'll put it on in the winter. Didn't need it this past winter.
John

The car should warm up quicker and have better driveability in cold weather or in cool, damp weather with the heat pipe in place. It's usually not needed in summer, but it can be useful in damp weather even in summer. If you live in dry desert country, you probably don't need one at all. Keep in mind that once the engine starts, the carburetor and intake manifold will immediately get much colder than the ambient temperature. Even in Florida in summer, an unheated carburetor can collect enough moisture to cause issues. Itr may not actually develop frost, but enough water can accumulate in the carburetor throat and intake manifold to interefere with idle and low speed operation. A carburetor can develop frost even at ambient temperatures well above freezing. If you live in an area that often has cool, damp mornings, you would probably do well to leave the heat pipe in place all year.