The Ford Barn

mleder · 10-16-2025, 10:28 PM

At the ever popular clinic of the Twin Cities Model A Ford Cub tonight, an oddity was presented. A member bought a "Rebuilt" carburetor off of the internet. It always ran rich and gas mileage was poor. The member opened it up and removed the GAV adjusting needle assembly. He had a new one on the bench and it measured 3/8' longer from the tip to the beginning of the threads that go into the cast iron. That was the problem of the rich running and poor mileage . That needle never really seated or closed enough. The question is what do you think this GAV needle was supposed to fit. A Model B Zenith?. I 've heard there is version of the Model A Zenith that has a removable seat for the GAV , does that take a shorter needle?. Can someone help with an explanation?.

Joe K · 10-17-2025, 08:07 AM

here are BUNCHES of Zenith variants used for various "other" motors/vehicles in the pre-war (and post war) period.

I have a cast iron Zenith looking externally very much like a Tillotson "X" but marketed for Clark Fork Lifts.

I have at least three others each stamped with a different number but reading in period literature as "for Model A/B."

These "aftermarket" Zeniths typically have a round aluminum "stamp spot" riveted with one center rivet to which a Zenith number was applied somewhere on the top half.

It seems that the period particularly before WWII was a "competitive" time for carburetor makers including Tillotson, Marvel-Schiebler, Rayco, Mochi, and others.

Interesting video about half an hour.

https://www.youtube.com/watch?v=s1DpeS9yq4k

Joe K

Gary WA · 10-17-2025, 08:53 AM

Quote:

Originally Posted by mleder

At the ever popular clinic of the Twin Cities Model A Ford Cub tonight, an oddity was presented. A member bought a "Rebuilt" carburetor off of the internet. It always ran rich and gas mileage was poor. The member opened it up and removed the GAV adjusting needle assembly. He had a new one on the bench and it measured 3/8' longer from the tip to the beginning of the threads that go into the cast iron. That was the problem of the rich running and poor mileage . That needle never really seated or closed enough. The question is what do you think this GAV needle was supposed to fit. A Model B Zenith?. I 've heard there is version of the Model A Zenith that has a removable seat for the GAV , does that take a shorter needle?. Can someone help with an explanation?.

They do vary in length. Should still screw all the way in! Depending on the year it may have a seat or something is restricting it!

Gary WA · 10-17-2025, 09:47 AM

The length going into carb are close in length, threads can be longer , there is also ones with threads not complete!reproductions!

Gary WA · 10-17-2025, 10:14 AM

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10-16-2025, 10:28 PM	#1
mleder Senior Member Join Date: May 2010 Posts: 205	Zenith Carburetor oddity At the ever popular clinic of the Twin Cities Model A Ford Cub tonight, an oddity was presented. A member bought a "Rebuilt" carburetor off of the internet. It always ran rich and gas mileage was poor. The member opened it up and removed the GAV adjusting needle assembly. He had a new one on the bench and it measured 3/8' longer from the tip to the beginning of the threads that go into the cast iron. That was the problem of the rich running and poor mileage . That needle never really seated or closed enough. The question is what do you think this GAV needle was supposed to fit. A Model B Zenith?. I 've heard there is version of the Model A Zenith that has a removable seat for the GAV , does that take a shorter needle?. Can someone help with an explanation?.

10-17-2025, 08:07 AM	#2
Joe K Senior Member Join Date: Jul 2010 Location: Cow Hampshire Posts: 5,018	Re: Zenith Carburetor oddity here are BUNCHES of Zenith variants used for various "other" motors/vehicles in the pre-war (and post war) period. I have a cast iron Zenith looking externally very much like a Tillotson "X" but marketed for Clark Fork Lifts. I have at least three others each stamped with a different number but reading in period literature as "for Model A/B." These "aftermarket" Zeniths typically have a round aluminum "stamp spot" riveted with one center rivet to which a Zenith number was applied somewhere on the top half. It seems that the period particularly before WWII was a "competitive" time for carburetor makers including Tillotson, Marvel-Schiebler, Rayco, Mochi, and others. Interesting video about half an hour. https://www.youtube.com/watch?v=s1DpeS9yq4k Joe K __________________ Shudda kept the horse. Last edited by Joe K; 10-17-2025 at 10:47 AM.