Carburetor intake air pre-heater as a cleaner

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jiminbartow
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Carburetor intake air pre-heater as a cleaner

Post by jiminbartow » Sun Jan 05, 2020 10:14 pm

Last year, I removed the manifold intake air pre-heater and replaced it with an air filter made to fit the NH intake opening, but since doing this, my T has not run as good as it did with the manifold heater, so I will be changing it back.

I like the thought of an air cleaner. Has anyone ever tried to convert the manifold heater into an air cleaner by packing it with a layer of some sort of filtering medium, such as steel wool, that is loose enough to allow for the flow of air but dense enough to filter the air? Thank you. Jim Patrick


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Re: Carburetor intake air pre-heater as a cleaner

Post by Scott_Conger » Sun Jan 05, 2020 10:37 pm

Jim

as a kid, I did what you did, for my dad's T. Just couldn't believe it didn't have an air cleaner. After installation, our experience was just the same as yours. Performance suffered, and these are not cars that have a lot to spare. Others disagree and claim to have seen no performance degradation. I expect you'll get lots of response from folks claiming success, so I will be interested to see if their set-ups result in similar success on other cars (yours).

My Healey has oil-soaked mesh air filters but is designed for them. I'd think steel wool would only work (slightly) if treated with oil or similar material. Then that presents both a fire and/or drippy mess to contend with.
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Re: Carburetor intake air pre-heater as a cleaner

Post by Les Schubert » Sun Jan 05, 2020 11:19 pm

I wonder if your air cleaner is big enough. I have noticed that sometimes people install air cleaners that people install are pretty small


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Re: Carburetor intake air pre-heater as a cleaner

Post by Dennis Prince » Sun Jan 05, 2020 11:34 pm

I am retired automotive mechanic and just couldn't drive a T on dirt roads without a air filter. I have 3 Ts with differing designs but all 3 work well,don't ice up and there is no change in performance. I will try to attach pictures of them.
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jiminbartow
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Re: Carburetor intake air pre-heater as a cleaner

Post by jiminbartow » Sun Jan 05, 2020 11:43 pm

Dennis. Your air cleaners appear to be connected, in some way, to a manifold air heater, so that you not only get the benefit of an air cleaner but also get the benefit of pre-heated intake air. My filter is about the same size as your third photo, but is not connected to a manifold intake air heater. Did you design and fabricate your air cleaners or did you purchase them? I can see where these would work. Thank you. Jim Patrick


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Re: Carburetor intake air pre-heater as a cleaner

Post by Dennis Prince » Mon Jan 06, 2020 12:24 am

Jim, I did fab them myself and the first one ts over the exhaust manifold and runs along the manifold giving it time to heat the air. I used a Model A air maze and the over sized filter element, a conduit connector a sink drain pipe and a radiator hose with the right bends in it. I built this over 10 years ago and haven't had any problems with it, I am always amazed at how much dirt the filter catches. The last picture is the air filter on my Funster (built for fun not speed) and I don't run it very hard and only when it is warm, the filter might not be big enough if I worked it like my other cars. It has no preheat but I am running the carb side draft and the intake is above the exhaust manifolds (it has split manifolds and duel exhaust
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Re: Carburetor intake air pre-heater as a cleaner

Post by Norman Kling » Mon Jan 06, 2020 1:07 am

I think it is because the T carburetors were not designed for an air cleaner. When anything restricts the air coming into the carburetor it restricts the high end performance because the fuel air mixture entering the engine is limited. It also affects the fuel mixture like driving with the choke partially closed. If you use a larger carburetor which was designed to use an air filter, it would run fine.
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Re: Carburetor intake air pre-heater as a cleaner

Post by Loftfield » Mon Jan 06, 2020 7:18 am

I also remember a post from a couple years ago that discussed dynamometer tests showing that the T lost 10% of its power when using a manifold heater. Because I am just wimpy I don't run my T's when it is THAT cold outside, also don't enjoy the hand crank with nearly solid oil in the transmission housing and having to jack up a rear wheel, so never use a manifold heater. That 10% increase in power is useful!


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Re: Carburetor intake air pre-heater as a cleaner

Post by Dennis Prince » Mon Jan 06, 2020 5:37 pm

I am curious if the theorists on the forum just go off someone elses test or if you try it for yourself. I have run my cars with and without the air filter and notice no change of any kind except the fact that the motor isn't ingesting dirt. My theory is if it's stupid but it works, it's not stupid. I am not trying to be offensive about it, I am just curious as to why someone would tell me why it won't work when it has been working for years.

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Re: Carburetor intake air pre-heater as a cleaner

Post by CudaMan » Mon Jan 06, 2020 5:47 pm

I found an air cleaner for an antique Clinton lawn tractor on Ebay and modified it to fit my T. My seat of the pants impression after three seasons of running is that the car has a small bit of extra power with the filter installed instead of the factory pre-heat tube.

I do remove the filter and re-install the factory pre-heat tube for winter driving. :)
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Re: Carburetor intake air pre-heater as a cleaner

Post by tdump » Mon Jan 06, 2020 6:31 pm

Looking at the Clinton Air filter,you might check the air filter for a Craftsman Eager 1 push lawnmower or similar Techumseh powered machine.I know my craftsman edger has it.It is a small filter made to twist and lock onto a bracket mounted to the carb with 2 small screws.
I can't use the preheater on my T pickup because the intake is fatter and seems to have the carb in a different from stock postion.I have been meaning to ask how to cope with it on the forum here and just keep forgeting to take a couple pics and ask.
If you can't help em, don't hinder em'

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Re: Carburetor intake air pre-heater as a cleaner

Post by Oldav8tor » Tue Jan 07, 2020 10:21 am

Aircraft engines use filters but you can pull a lever and direct hot air (carb heat) from a shroud around the exhaust into the carb to melt ice if it forms. Since the temp of air passing thru a venturi drops, ice can form even when it is warm out.... depends a lot on the humidity. You normally don't run carb heat continuously unless it's icing badly. Applying carb heat will see the rpm drop - power loss due to enriching the mixture.

When running a carb heater on a T I would think you could minimize power loss by adjusting the carb mixture control. Of course, that does nothing to keep crud out of the engine.

I run a carb heater but would love to come up with a way to filter the air going in to the carb. Without the heater the intake manifold just beyond the carb gets very cold so I'm torn as to what to do.
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Re: Carburetor intake air pre-heater as a cleaner

Post by John M Maslack » Sat Jan 11, 2020 10:34 pm

The biggest problem with an air cleaner on a T is that the carb isn't pressure balanced. The bowl is vented to the atmosphere and when you add any thing that restricts the flow, the carb tends to load up. This could probably be cured by adding a tube from the vent to the air intake on the carb..This is done sometimes on model a carbs by plugging the vent and machining a passage to the intake side. In more modern down draft carbs the tube you see sticking up in the intake is there to accomplish this. Apparently no one figured this out until the 30's..


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Re: Carburetor intake air pre-heater as a cleaner

Post by Mark Osterman » Sun Jan 12, 2020 11:32 am

Was just wondering about those vintage air valves found on intake manifolds. They are designed to let more oxygen to mix with the gas vapors. If you restrict the air with a filter on one end ... could you add it at the other? Or would drawing unfiltered air on that end just suck in more debris? Just thinking with my thumb on the phone keyboard. 😀

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