The Ford Barn

hangarb7 · 06-16-2015, 08:24 PM

holy cow, now I've seen everything.

I bought my '30 Tudor which was restored by two older gents many years ago, and it has been a decent tourer although I have struggled to keep it running well as I learn over the last 7 years. Part of that has been in no small part to the fact that the old gents left a lot of parts off the car. Too many to list.

On a tour last week (I posted this part on another thread) my car would suddenly not idle and needed a lot of throttle to start, which is extremely unusual, as this car starts very quickly and easily, and runs pretty well. Diagnosed as dirt in the carb.

I take the carb apart and it was clearly rebuilt at some point but dirt inside so I clean all the parts, blow it out and ready to reassemble. Get out the Les Andrews book and also my Rex Rehaus book on carb rebuilding and both of them mention a Secondary Well.

What? Not only does my carb not have one, but the spare carb I bought separately at a swap meet ALSO doesn't have one. What's up with that? Did old timers just leave them out? I can see the threads in the hole, and I can see the end of the cap jet at the bottom. Ordering two from Snyders tomorrow.

Why did they just leave them out?

Thanks,

JackD

Gary Karr · 06-17-2015, 12:54 AM

If you have the threads in the well and it is indeed a Zenith-1, it should have the brass secondary well. The double venture carbs did not use the brass screw-in secondary wells.

hangarb7 · 06-17-2015, 07:09 AM

Thanks Gary. Yep, they are both Zenith-1 stamped on the side and have threads.

Is the secondary well difficult to get out? Is it possible they damaged the brass part trying to remove it?

Anyone know the function of the Secondary Well? I can't find anything written about it to explain exactly what it does.

Interesting that this thread got 147 views but only one comment. Again, thanks, Gary.

JackD

Rex_A_Lott · 06-17-2015, 09:58 AM

If the car was a "decent tourer" as you say it did not suddenly start not idling well because some old gents left out parts 7 years ago.
Clean it, blow it out good and chances are it will again be a decent tourer.
Be sure to check the float, but dont screw with the level setting if it was OK before.
Good Luck

mrtexas · 06-17-2015, 10:02 AM

https://sites.google.com/site/mrtexa...ome/modelacarb

The unique feature of the Zenith carburetor is the addition of a secondary well open to the atmosphere to the simple carburetor. This was the basis for the 1905 US patent by Francois Baverey of the French Carburateurs Zenith Co.

The secondary well is open to the atmosphere allowing air as well as fuel to be sucked into the intake thru the cap jet. As the rpm increases the air/fuel ratio increases providing a leaner mixture.

The secondary well increases air/fuel ratio(leaner) as rpm increases counteracting the simple carburetor decrease in air/fuel ratio(richer). The combined result is a more constant air/fuel ratio over all rpms.

Another feature of the secondary well is that it fills at idle and when the throttle is opened, it empties and acts like an accelerator pump.

Bottom one has secondary well. Notice the spacing of the two jets. The spacing is different depending on whether there is a secondary well or not. Note also nib for dual venturi.

Mitch//pa · 06-17-2015, 10:07 AM

Sponsored Links (Register now to hide all advertisements)

http://www.modela.org/secondary_well.html

hangarb7 · 06-17-2015, 11:09 AM

THANK YOU VERY MUCH. THIS NOT only explains what it is for, but this also explains why my car acts as it does! I never had any rapid acceleration of the engine speed and I just explained it away to myself that it was because there was no accelerator pump. But apparently the secondary well acts as that... and the article also speaks of the different types and being careful about the comp jet running into it at the bottom. GREAT advice from all.

Thanks,

JackD

TinCup · 06-17-2015, 04:37 PM

Some great info here as well. These animations give the novice a better idea of how the carb works.
Model A Basics

Rex_A_Lott · 06-17-2015, 09:40 PM

Quote:

Originally Posted by TinCup

Some great info here as well. These animations give the novice a better idea of how the carb works.
Model A Basics

Thanks for posting this link, now I have a new website to look over, and it appears to be a good one!
There is also a link to a carb rebuild by Mr Tom Endy that I enjoyed and was very thorough.

06-16-2015, 08:24 PM	#1
hangarb7 Senior Member Join Date: May 2014 Location: North Versailles, PA Posts: 146	zenith-1 carb...missing part? holy cow, now I've seen everything. I bought my '30 Tudor which was restored by two older gents many years ago, and it has been a decent tourer although I have struggled to keep it running well as I learn over the last 7 years. Part of that has been in no small part to the fact that the old gents left a lot of parts off the car. Too many to list. On a tour last week (I posted this part on another thread) my car would suddenly not idle and needed a lot of throttle to start, which is extremely unusual, as this car starts very quickly and easily, and runs pretty well. Diagnosed as dirt in the carb. I take the carb apart and it was clearly rebuilt at some point but dirt inside so I clean all the parts, blow it out and ready to reassemble. Get out the Les Andrews book and also my Rex Rehaus book on carb rebuilding and both of them mention a Secondary Well. What? Not only does my carb not have one, but the spare carb I bought separately at a swap meet ALSO doesn't have one. What's up with that? Did old timers just leave them out? I can see the threads in the hole, and I can see the end of the cap jet at the bottom. Ordering two from Snyders tomorrow. Why did they just leave them out? Thanks, JackD

06-17-2015, 12:54 AM	#2
Gary Karr Senior Member Join Date: Jun 2010 Location: San Diego, CA Posts: 1,487	Re: zenith-1 carb...missing part? If you have the threads in the well and it is indeed a Zenith-1, it should have the brass secondary well. The double venture carbs did not use the brass screw-in secondary wells.

06-17-2015, 07:09 AM	#3
hangarb7 Senior Member Join Date: May 2014 Location: North Versailles, PA Posts: 146	Re: zenith-1 carb...missing part? Thanks Gary. Yep, they are both Zenith-1 stamped on the side and have threads. Is the secondary well difficult to get out? Is it possible they damaged the brass part trying to remove it? Anyone know the function of the Secondary Well? I can't find anything written about it to explain exactly what it does. Interesting that this thread got 147 views but only one comment. Again, thanks, Gary. JackD

06-17-2015, 09:58 AM	#4
Rex_A_Lott Senior Member Join Date: Jun 2011 Location: Upstate South Carolina Posts: 794	Re: zenith-1 carb...missing part? If the car was a "decent tourer" as you say it did not suddenly start not idling well because some old gents left out parts 7 years ago. Clean it, blow it out good and chances are it will again be a decent tourer. Be sure to check the float, but dont screw with the level setting if it was OK before. Good Luck

06-17-2015, 10:02 AM	#5
mrtexas Senior Member Join Date: May 2010 Location: Sugar Land, TX Posts: 4,395	Re: zenith-1 carb...missing part? https://sites.google.com/site/mrtexa...ome/modelacarb The unique feature of the Zenith carburetor is the addition of a secondary well open to the atmosphere to the simple carburetor. This was the basis for the 1905 US patent by Francois Baverey of the French Carburateurs Zenith Co. The secondary well is open to the atmosphere allowing air as well as fuel to be sucked into the intake thru the cap jet. As the rpm increases the air/fuel ratio increases providing a leaner mixture. The secondary well increases air/fuel ratio(leaner) as rpm increases counteracting the simple carburetor decrease in air/fuel ratio(richer). The combined result is a more constant air/fuel ratio over all rpms. Another feature of the secondary well is that it fills at idle and when the throttle is opened, it empties and acts like an accelerator pump. Bottom one has secondary well. Notice the spacing of the two jets. The spacing is different depending on whether there is a secondary well or not. Note also nib for dual venturi. Last edited by mrtexas; 06-17-2015 at 10:12 AM.

06-17-2015, 10:07 AM	#6
Mitch//pa BANNED Join Date: May 2010 Location: Bucks County, PA Posts: 11,454	Re: zenith-1 carb...missing part? Sponsored Links (Register now to hide all advertisements) http://www.modela.org/secondary_well.html

06-17-2015, 11:09 AM	#7
hangarb7 Senior Member Join Date: May 2014 Location: North Versailles, PA Posts: 146	Re: zenith-1 carb...missing part? THANK YOU VERY MUCH. THIS NOT only explains what it is for, but this also explains why my car acts as it does! I never had any rapid acceleration of the engine speed and I just explained it away to myself that it was because there was no accelerator pump. But apparently the secondary well acts as that... and the article also speaks of the different types and being careful about the comp jet running into it at the bottom. GREAT advice from all. Thanks, JackD

06-17-2015, 04:37 PM	#8
TinCup Senior Member Join Date: May 2010 Location: OKC / Tonkawa, Ok. Posts: 1,977	Re: zenith-1 carb...missing part? Some great info here as well. These animations give the novice a better idea of how the carb works. Model A Basics __________________ Oklahoma City Model A Restorers Group.