Air intake for Zenith S4BF Carburetor

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Topic author
BarnesvilleT
Posts: 61
Joined: Mon Nov 14, 2022 8:26 am
First Name: William
Last Name: Hallada
* REQUIRED* Type and Year of Model Ts owned: 1926 Medel T Coupe
Location: Barnesville, GA

Air intake for Zenith S4BF Carburetor

Post by BarnesvilleT » Fri Mar 17, 2023 9:57 pm

The engine I have for my 26 Coupe came with the S4BF on it without a hot air intake.
I am getting ready to try and start the engine and was wondering what I could do to put an intake
on the carb. At this time I don't even know if the carb is any good. I have found some old brochures for
the kit that was sold and it shows a hot air intake attached to the carburetor using some sort of flex tubing.
I have a stock hot air intake and was thinking of cutting it and putting the flex pipe on it and running that to the
intake of the carb. There are some holes in the neck of intake and I want to be sure if they should be open or sealed off when
the pipe is inserted into the carburetor. I did buy a foam intake from Lang's but it will not insert into the opening.
Any help or input would be appreciated.


Scott_Conger
Posts: 6431
Joined: Sun Jan 06, 2019 11:18 am
First Name: Scott
Last Name: Conger
* REQUIRED* Type and Year of Model Ts owned: '13, '15, '19, '23
Location: Clark, WY
Board Member Since: 2005

Re: Air intake for Zenith S4BF Carburetor

Post by Scott_Conger » Sat Mar 18, 2023 9:49 am

The S4BF is an excellent carb, with some caveats. Unlike carbs originally supplied with the car, there is no richness adjustment and no cold-start setting other than the choke. With ALL of the kit installed, meaning the "hot air pipe", the vent/inlets on the carb are kept closed for the greatest heat when first started and then opened as ambient temps dictate.

Although you cannot adjust the main jet richness, you can and must adjust the idle/low speed mixture. This is the only adjustment and is made at the carb, not from the interior of the car. Once set, it is set and no more fooling around with it.

Because the main jet is fixed and cannot be regulated for richness either for starting or altitude, ya gets what ya gets. If they have the original/correct jets and are not worn oversize, it should be a good carb with excellent performance. If jets are worn or wrong, it may be hard starting or not perform very well. Typically, the only certain way for an S4BF to perform on a car is if it is fitted with a custom adjustable jet.

When these carbs were new, by far, the cars to which it would be fitted were relatively new and very standardized...a fixed jet worked fine. Today, with varying performance via performance cams, large valves, etc., there is less likelihood that the carb will be correctly jetted for any given engine, thus the need for the adjustable jet.

So here's my unsolicited advice: since you are trying to start an engine for the first time, do NOT handicap that effort with an unknown-performing carb. Buy or rebuild an NH or Kingston L-4 carb and be CERTAIN that you have a carb capable of being tuned to the desire of your particular engine. Once it is running well, starting reliably, and you know what the car is capable of doing, THEN swap out the original style carb for an accessory carb. At that point, if the car is hard starting or smokes, or fouls plugs, you'll know it's the carb and not a lame engine.
Scott Conger

Tyranny under the guise of law is still Tyranny

NH Full Flow Float Valves
Obsolete carburetor parts manufactured


Topic author
BarnesvilleT
Posts: 61
Joined: Mon Nov 14, 2022 8:26 am
First Name: William
Last Name: Hallada
* REQUIRED* Type and Year of Model Ts owned: 1926 Medel T Coupe
Location: Barnesville, GA

Re: Air intake for Zenith S4BF Carburetor

Post by BarnesvilleT » Sat Mar 18, 2023 8:10 pm

Scott thanks for info. I am looking for the carb and an intake manifold. Have been in contact with
someone in Alabama and I think he can fix me up with an NH and the right manifold. I will let you know how it works out.
Again thank you, I appreciate your advice.

Bill H.


Scott_Conger
Posts: 6431
Joined: Sun Jan 06, 2019 11:18 am
First Name: Scott
Last Name: Conger
* REQUIRED* Type and Year of Model Ts owned: '13, '15, '19, '23
Location: Clark, WY
Board Member Since: 2005

Re: Air intake for Zenith S4BF Carburetor

Post by Scott_Conger » Sat Mar 18, 2023 8:14 pm

You are most welcome.

If in good shape, the Zenith is a wonderful carb...I just didn't want to see you struggle starting the engine with an unknown commodity...might have been just fine, but you just never know.

Best of luck and keep everyone posted with your progress
Scott Conger

Tyranny under the guise of law is still Tyranny

NH Full Flow Float Valves
Obsolete carburetor parts manufactured

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