8N carburetor for T?

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Tom Hicks
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8N carburetor for T?

Post by Tom Hicks » Fri Nov 08, 2019 10:14 am

Would one of these work better than an NH?

https://www.ebay.com/itm/Brand-New-Carb ... 6ac228402d
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Norman Kling
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Re: 8N carburetor for T?

Post by Norman Kling » Fri Nov 08, 2019 10:50 am

From the pictures it looks like it would be up draft. The manifold on the T is side draft, so it would require a change of the intake manifold to make it fit on a T.
Norm


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Tom Hicks
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Re: 8N carburetor for T?

Post by Tom Hicks » Fri Nov 08, 2019 10:53 am

Norman Kling wrote:
Fri Nov 08, 2019 10:50 am
From the pictures it looks like it would be up draft. The manifold on the T is side draft, so it would require a change of the intake manifold to make it fit on a T.
Norm
I think I could make an adapter.

The question is, would the 8N carburetor perform better than the NH on a T?
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Re: 8N carburetor for T?

Post by Jim-B » Fri Nov 08, 2019 12:42 pm

I used a 9N carb on a T with a Chevy overhead conversion and it runs strong. Not the same thing?


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Re: 8N carburetor for T?

Post by StanHowe » Fri Nov 08, 2019 3:29 pm

They are about the same level of technology. No accelerator circuit but the TSX Marvel Schebler copy does have an idle air adjustment and main jet adjustment. Other than that they are a puddle of gas with a hole to get it into the air stream flowing through it.
That said, those repros are actually pretty good carburetors as long as you don't plan on ever rebuilding it. The kits available from Tisco and other sources do not fit them well. However, the entire carburetor is cheaper than the good kits for the TSX series Marvel Scheblers.

I have half a dozen little Ford tractors, they all run Marvel Schebler carbs, some get so worn they are not really worth rebuilding. It is a cheap and simple fix to put one of these on and be done with it for awhile.

Would I run one on a T? NO, but then I have hundreds of carbs to choose from. As far as will it run well????? Probably about the same or slightly better than an NH. Still no accelerator circuit. Is it worth the effort to make all the linkage and manifold to make it work. Not to me but I'm busier than a lot of people.

Not that this has much to do with that but I have 2 Ford 9N's, one Ford 8N, one
Ford NAA, one Ford 600, one
Ford 801, one Ford 4000 diesel, two Allis Chalmers B's, one Allis Chalmers WC, one Oliver 60, one IHC 300 Utility, one IHC 454 Utility, two Ferguson TO-30's, one Ferguson TO-35, two Case S's and my latest treasure, an Earthmaster -- one of the few survivors of fewer than 2,000 made in LA in the 40's and 50's -- and a Barnett, made from Model A parts in the 40's. Should be 20 if I counted right. Seems like there is another but I can't think what it is.

Nearly all of the gas engine ones run Marvel Schebler carbs except the Earthmaster. It has a funny little Zenith. I just bought the AC WC, the Oliver and the Earthmaster at an auction about 3 weeks ago. Should have bought more. Helpful hint: If you are rebuilding old Marvel Schebler carbs, the 9N carb and the later 8N carbs are not the same even tho they look the same externally. The TSX 33 for the 9n and the TSX 214 take a different idle jet. The only kits available are for the 214. If you put the idle jet from that kit in the 33 it will not idle. Keep the old idle jet and use it. =)


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Re: 8N carburetor for T?

Post by Tom Hicks » Fri Nov 08, 2019 6:08 pm

StanHowe wrote:
Fri Nov 08, 2019 3:29 pm
They are about the same level of technology. No accelerator circuit but the TSX Marvel Schebler copy does have an idle air adjustment and main jet adjustment.

Would I run one on a T? NO, but then I have hundreds of carbs to choose from. As far as will it run well????? Probably about the same or slightly better than an NH. Still no accelerator circuit.
Thank you for your input, it is both appreciated and respected.

I put one of these on my 8N and it really runs great, which is why I was wondering about how it would work on a T. At $30 apiece they would be a throw away when they needed a rebuild. If 1/5 the cost of a rebuilt NH, and a better performer, they might make sense.

And I can't say I am impressed by the NH, but I don't really understand carburetion. Could you give your opinion on the three "secret passageways" that have to be cleaned? What are they for? How do they work? And does it make any sense to put plugs in the ends after cleaning to keep dirt out? It seems like that is just blocking up what you just cleaned.
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Re: 8N carburetor for T?

Post by Tom Hicks » Sat Nov 09, 2019 1:02 am

The passages shown in this picture.
What do they do?
How do they do it?
Does sealing them up after cleaning them out defeat their purpose?

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Re: 8N carburetor for T?

Post by Corey Walker » Sat Nov 09, 2019 9:46 am

Those passages are for the gasoline to flow through at idle when the throttle butterfly is partially closed. Fuel is drawn from the mixing chamber and it flows through the passages until it exits inside the throat of the carburetor via the 2 holes. As the throttle is opened more air flows through the main bore and the venturi effect draws gasoline from the main puddle. The passage under the name tag is an air bleed to allow some air in when the choke is closed to replace the fuel being sucked through the oassages but it does not intersect them. The plugs were used to seal where the passages were drilled making the intersecting bores a passage from the mixing chamber to the throat.
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Re: 8N carburetor for T?

Post by Tom Hicks » Sat Nov 09, 2019 11:31 am

Corey Walker wrote:
Sat Nov 09, 2019 9:46 am
Those passages are for the gasoline to flow through at idle when the throttle butterfly is partially closed. Fuel is drawn from the mixing chamber and it flows through the passages until it exits inside the throat of the carburetor via the 2 holes. As the throttle is opened more air flows through the main bore and the venturi effect draws gasoline from the main puddle. The passage under the name tag is an air bleed to allow some air in when the choke is closed to replace the fuel being sucked through the oassages but it does not intersect them. The plugs were used to seal where the passages were drilled making the intersecting bores a passage from the mixing chamber to the throat.
Thanks, that is really interesting. Were these types of passages used on other brands of carburetors, or were they unique to the NH?
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Re: 8N carburetor for T?

Post by Corey Walker » Sat Nov 09, 2019 12:44 pm

It was the same principle but required a lot more machining and parts. The G for example has a pick up tube that originates in the pool of gas in the depression of the jet then screws to a fitting allowing the gasoline to pass from the mixing chamber to a passage drilled to the carburetor throat. This passage is sealed with a screw. So it does the same thing but is more costly to produce.
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Re: 8N carburetor for T?

Post by Corey Walker » Sat Nov 09, 2019 12:49 pm

The 1913 Holley S was similar but the pick up tube was soldered to the mixing chamber cover and the holes for the gas to flow were machined to line up for gas flow. The air bleed, which also served as an overflow drain, was a hole drilled from the bottom on both the G and S.
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Tom Hicks
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Re: 8N carburetor for T?

Post by Tom Hicks » Sat Nov 09, 2019 1:25 pm

That is old and amazingly simple technology. Impressive that they figured out how to make it work so long ago.

How about the carburetors that are actually considered good for a T, like the Stromberg OF. Does it have secret passages too? I am guessing not, part of the reason it is a superior carburetor...
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Re: 8N carburetor for T?

Post by StanHowe » Sat Nov 09, 2019 2:36 pm

The OF has three circuits. Low speed/idle has a separate jet. High speed has its own jet. The Economizer circuit bleeds air to the main jet to lean it at low power/low speed requirements.


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Re: 8N carburetor for T?

Post by Tom Hicks » Sat Nov 09, 2019 5:51 pm

Thanks for all of your replies. Interesting stuff.

A rebuilt Stromberg OF runs $600 and up. A new 8N carburetor is $30 and runs strong on an 8N. So my last question is,

would an 8N carburetor run as well or better than a Stromberg OF on a Model T?
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