MTFCA Forum

Bonnie, my 24 touring, ran fine yesterday on a 38-mile ride to a club fund raiser and for the first seven or eight 2-mile passengers rides through town, then started running rough. Replacing a broken spark plug wire and one coil effected no improvement. All 4 spark plugs were extremely sooty (but dry), indicating a rich mixture condition. It seemed to get worse, and I and others helping could smell raw fuel in the exhaust, and there was occasional popping out of the exhaust. Adjusting the mixture control made no difference, and it wasn’t leaking to indicate an issue with the float. It eventually got so bad that it would just barely go down the road, so I decided to leave it in a local club member’s garage. Today I went back armed with a rebuilt NH I got from Corey Walker last winter. That fixed the issue, proving that the carburetor was the culprit.

However, upon looking through the bore of the removed straight through NH carburetor, I couldn’t see through it, then noticed a third butterfly plate just downstream of the choke plate. There is no external control, but when the carburetor is right side up it closes off the bore, and when upside down flops open. Apparently it is intended be closed when the engine isn’t running, then open due to airflow when the engine is running. The club member who let me use his garage has been driving Model T’s for well over 50 years and said he’d never seen one like that, and none of the several NH’s (straight through or not) in his collection has this feature. We are thinking it might be a feature to keep mud wasps out?

Has anyone here ever seen an NH like this or really know it’s purpose? You can tell from outside by a screw on the engine side of a mounted carburetor, which is apparently the pivot for the plate. Is it possible that this plate became stuck in some intermediate position causing the over-rich condition?

Are you sure that is a NH? It looks like a Kingston L4 to me. The Kingston has a flapper valve between the choke and the throttle.
Norm

Looks like Western Auto or Simmons. That looks like heater post on exit end of carb.

The Kingston L4 has a little flapper like you describe. I take it there is no dataplate on the Carb?

There is a data plate on the carburetor. I have no clue as to its originality.

The L-4 flapper is near the throttle plate, not the choke plate. That is not an L-4.

Dan Hatch wrote: ↑

Tue Jul 05, 2022 9:05 pm

Looks like Western Auto or Simmons. That looks like heater post on exit end of carb.

That is exactly what it is. Someone, somewhere down the line changed the name plate on the carburetor for some reason. The flapper is supposed to help with smoothing out the low speed idle characteristics.



Here are some links from the Old Forum as well as this one:

http://www.mtfca.com/discus/messages/70 ... 1486770519
http://www.mtfca.com/discus/messages/33 ... 1372906796
http://www.mtfca.com/discus/messages/41 ... 1406346710
viewtopic.php?f=2&t=23917&p=183527&hili ... ns#p183527
viewtopic.php?f=2&t=1790&p=15744&hilit=simmons#p15744

Thank you Pep! It ran great until it didn’t. Is it likely that the flapper stuck and caused the over rich condition, or would the issue more likely be somewhere else?

I'd suspect the flapper. It may have some wear that allows it to jam. I'd think the flapper arrangement could improve low speed performance and allow a slightly leaner mixture. If the straight through NH has a larger venturi than a standard NH, it could degrade low speed performance somewhat, while improving high speed performance a little. The flapper may have been an attempt to improve the carburetor's performance across a wider speed range.

That’s not a Kingston L4. The screw is on the wrong side of it to be for the flapper. Doesn’t look like the Kingstons that I have.

The brass tag says "Simmons super power carburetor".

Allan from down under.

That's not the same carburetor Allan - he posted it for comparison.

We are looking at two different carburetors. Pep C's has the Simmons tag on it. Miles B's has a "Ford NH" tag on it.
I can't tell if Miles' carburetor has the heater coil or not. The Simmons/Wizard carburetors were available either with or without that heater coil. Most do seem to have the coil, but I have seen one that never did.

Despite the "NH" tag, it appears that Miles' carburetor is a Simmons/Wizard by any name.

Wayne, my carburetor doesn’t have the heater wire, but as Dan Hatch noticed it does have the post, so it did have the heater at one time. Now that I know the differences between an NH and a Simmons I’m convinced it’s a Simmons someone put a Ford NH tag on way back when. With the carburetor mounted on the engine you’d have to look REALLY close to tell it wasn’t an NH. Thanks to all for helping to solve this minor mystery.

With modern gasoline, I would not recommend hooking up the heater wire. I seriously doubt using it would hurt anything, however, I also doubt having the wire hooked up and turned on really helped much with the poor fuels back in the day. It has been speculated, that the circle of coil likely did more good by stirring up the air flow than it ever did by the little bit of heat it could have warmed the poor fuel with in the first place. I would be tempted to make a replacement out of common steel wire and mount it just for that purpose, although I doubt even there it would make that much difference.

I would be curious to hear what you find checking your carburetor out? Is the flapper hanging up? Would a bit of work with a file fix it and get it working right again?

Wayne Sheldon wrote: ↑

Thu Jul 07, 2022 3:08 am

… I would be curious to hear what you find checking your carburetor out? Is the flapper hanging up? Would a bit of work with a file fix it and get it working right again?

I have the carb from my express wagon to take as a spare on the Hamilton tour, so I probably won’t take time to really get into the Simmons until I get back. But I have noticed that the flapper valve doesn’t always open when I turn the carb upside down, and I have to shake it a bit to get it to flop open. There is a sticky film on the throttle plate that looks like the thread sealant I used on the sediment bowl and fuel shutoff valve, but there is no evidence of it upstream of the jet. I was wondering if I could just remove the flapper?

mbowen wrote: ↑

Thu Jul 07, 2022 12:08 pm

Wayne Sheldon wrote: ↑

Thu Jul 07, 2022 3:08 am

… I would be curious to hear what you find checking your carburetor out? Is the flapper hanging up? Would a bit of work with a file fix it and get it working right again?

I have the carb from my express wagon to take as a spare on the Hamilton tour, so I probably won’t take time to really get into the Simmons until I get back. But I have noticed that the flapper valve doesn’t always open when I turn the carb upside down, and I have to shake it a bit to get it to flop open. There is a sticky film on the throttle plate that looks like the thread sealant I used on the sediment bowl and fuel shutoff valve, but there is no evidence of it upstream of the jet. I was wondering if I could just remove the flapper?

The flapper is key to its design. Note the little brass jet @ the base when closed. Thats the idle circuit. I doubt it would function well without the functioning flapper. The flapper is a calibrated/weighted pot metal piece. It comes out easily. You need to sand/file on it to get it to move freely.

A close look at the Ford Tag rivets will tell you someone switched tags, perhaps because they did not have the proper tag or wanted to upgrade the carburetor to sell it for more money, because the Ford carburetors are more desirable and sell for more money.

There are three Ford carburetors to choose from after 1920.

1. The Ford Full Flow.

2. The Ford-F

3. The Ford-NH