what does this adjust

[silversink]

On one of my Zeniths I have this adjustment on the bottom. I have searched and haven't found anything describing it. I cant get the picture to load. It is a needle valve in the place of the plug on the bottom of a Zenith Carb bottom.

[BILL WILLIAMSON]

"MAYBE" it's just an old pet cock type drain valve, ued to replace a MISSING drain plug??----Bill W.

[Bruce Lancaster]

Some industrial/farm variants of A and B carbs have an adjustable main jet...these variant ones are somewhat modified and generally lack a GAV, but it looks to me that the adjustment would fit right into a Ford version.

[160B]

Here is a photo of the lower section of the adjustable main jet showing the adjustable needle.

[silversink]

Originally Posted by 160B

Here is a photo of the lower section of the adjustable main jet showing the adjustable needle.

Mine is a little different but the same principle. Is the inside jet different or the same as other Zenith's . Can I eliminate it without screwing up the balance of the carb?

[Bruce Lancaster]

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I'd compare the actual jets, but I would think the adjustable one would have to be larger both to accommodate the needle and to allow some range beyond standard.

[FL&WVMIKE]

I have one of those, but I never ran it. I think that it was an after-market device, to "fine tune" your carburetor. I don't believe it was a Ford product.
MIKE (mikeburch)

[Bruce Lancaster]

I've only seen them on industrial variants, no GAV and generally used at a steady RPM. A's an B's already had the GAV, so this would seem redundant!

[BILL WILLIAMSON]

Never saw one!! AMAZING what I've lurned here!! FAR MORE than I've contributed!!---Bill W.

[Bruce Lancaster]

I've turned up a number of carbs based on the Model B Zenith and seen several Model A based ones, all without real provenance but said to be from agricultural machines. I think every one is a bit different from the others. None have the GAV, several have the adjustable jet. I assume all were from post 1931 Ford powered machinery, but don't really know. They all came from junk boxes at fleamarkets...I wonder if anyone actually knows, from actual machinery or elderly Zenith catalogs.

[Drive Shaft Dave]

About twenty years ago or so Model A News ran an article about some adjustable jets such as you have shown here.

[Manuel]

I came across a Model A/B type carby once at a swap meet that was identical to look at but was 2 or 3 times larger??
Heavy too!!

Manuel in Oz

[silversink]

the carb that has this does have a GAV and was on a running A. When I tried to run the carb with out the needle valve it ran like crap , but with it ran OK - just not exceptional. I want to rebuild the carb but don't want to put the money in one that isn't right for the 29

[Bruce Lancaster]

I think the poor running without the valve would be because it must have a large main jet to get it into the normal range with a needle occupying a lot of the area. Just find an original Ford jet to run without the gadget.

[Glenn Thoreson]

Tractor/industial aplication. If it works properly, why change it?

[BILL WILLIAMSON]

With that set up, running it on a stationary engine with a governor, you could set it perfectly, to a GNAT'S EYEBROW!
Bill W.

[Walt Dupont--Me.]

Originally Posted by BILL WILLIAMSON

With that set up, running it on a stationary engine with a governor, you could set it perfectly, to a GNAT'S EYEBROW!
Bill W.

I've got all I need to build that bug. All I need is another project. I love. Walt

[BILL WILLIAMSON]

Originally Posted by Walt Dupont--Me.

I've got all I need to build that bug. All I need is another project. I love. Walt

Walt, I love that "BUG", even with bird poop ALL over it & the driver looks like a TWIN to my now deceased, hot rodder brother, Gary Eakles! (RIP!)
Bill W.

[AL in NY]

I just picked up a Model "B" Zenith at the National Meet in St. Louis last week that had the same sort of adjustable main jet. The carb was painted red, so I'm assuming it's off of some sort of Model A/B driven machinery. The carb has a "GAV" adjustment and it also has the throttle valve enrichment system, so it is a standard "B" carburetor. I think this would be a nice option for guys who would travel up and down the Rockies. It's an easy way to tune the carburetor for different altitudes. But then again, the "GAV" would do that. Just my 2 cents.

[FL&WVMIKE]

Originally Posted by Walt Dupont--Me.

I've got all I need to build that bug. All I need is another project. I love. Walt

WALT .......................
A friend of mine and I built a replica of the "BUG" several years ago.
If you have any questions, let me know.
MIKE (mikeburch)
CLICK ON PHOTO TO ENLARGE - Twice