Zenith Carborator

I have a Zenith carburator on my 1923 Buick model 45. The previous owner replaced the Marvel carb. with this Zenith. System runs fine but lean. The only number I can find on this carb. is 200. I need to know where is the needle so I can adjust the mixture. If I find the needle, which way do I turn it to make it richer?

Tom,

I don't seem to see a Model 200 listed anywhere for Zenith. You may want to check the following link and see if you find a carburetor that looks like yours. If you need me to stop by and help you with it, let me know.

http://www.carburetormanuals.com/products/carbmanuals/zenith.html

Hopefully you can find the right carb on this site and you can order a manual for it.

Tom - you NEED more information.

Zenith made dozens of models of updraft carburetors (none of which is a model 200).

Within each model, there are from a few to hundreds of different calibrations.

The reason for all of the different carburetors is different size and styles of engines.

MOST Zenith O.E. (original equipment) carburetors would have an adjustable idle and a fixed main metering jet.

VIRTUALLY ALL A.M. (aftermarket) carburetors would have both an adjustable idle AND an adjustable main metering jet.

Some idle adjustors meter air; some idle adjustors meter fuel.

If the idle adjustor meters air, turning the screw in a clockwise direction will make it richer.

If the idle adjustor meters fuel, turning the screw in a counterclockwise direction will make it richer.

The idle adjustor will be a brass screw with a knurled head retained by a cylindrical spring generally near the top of the carburetor. If the screw is removed, MOST will come to a point (some sharp points, some rounded points).

IF the carburetor has an adjustable main metering circuit, the adjustor will GENERALLY be a "T" located near the bottom and toward the end opposite the air intake. I cannot recall a high speed adjustor that meters air (but there may be one somewhere). Virtually all will meter fuel, thus turning the high speed adjustor in a counter-clockwise direction will make it richer.

Another possibility is that the carburetor is set up for a pressure fuel pump and you are running gravity feed. In this case THE CARBURETOR WILL RUN LEAN, REGARDLESS OF HOW YOU ADJUST IT (check the tongue-in-cheek comments in my signature).

Please re-read my first sentence!

Zenith carbs produced from about 1935~1979 are identified by a round tag about the size of a dime with a rivet holding the tag to the carburetor body. To remove the tag, a hammer and chisel are necessary.

Zenith carbs produced from about 1980~currect have the identification number STAMPED (NOT RAISED) in one of two locations:

(1) longitudally on the edge of the mounting flange where the carb bolts to the manifold

(2) in a semi-circle somewhere on the top (throttle body) casting

The numbers on the flange are huge almost 3/16 of an inch tall.

The numbers in a semi-circle are approximately 1/16 of an inch tall (maybe the thickness of the lead in a lead pencil!). The entire semi-circle can be covered by a garden pea!

Generally, to find the stamped numbers, one needs to clean the outside of the carburetor; and assemble the following "tools":

(1) magnifying glass

(2) strong light

(3) pair of "young eyes"

Try the above adjustments. If no help, find the number and repost here.

Jon.

Carbking,

Thanks. Tom is a member of my local AACA Chapter. I am relatively close to Tom and have younger eyes than he does. I will try to stop by sometime soon and help him figure out what he has on the car. If you happen to know what the correct original carburetor should be for his car, or a source of a good appropriate available replacement, I am sure he would be interested.

Carbking,

Thanks. Tom is a member of my local AACA Chapter. I am relatively close to Tom and have younger eyes than he does. I will try to stop by sometime soon and help him figure out what he has on the car. If you happen to know what the correct original carburetor should be for his car, or a source of a good appropriate available replacement, I am sure he would be interested.

Matthew - the original carburetor would have been a Marvel.

While there are some who would always keep everything original, my professional opinion is that one could get better carburetion than the Marvel is capable of by turning the manifold upside down, removing the hood, and hiring a 15-year-old to stand on the running board and pour fuel into the engine from a leaky boot!

Tom's model 45 should have a 242 CID 6 cylinder. There are a number of different Carter, Stromberg, and Zenith carbs (different features, different prices) that would work better to much much better than the Marvel.

Choosing one of these is a compromise of:

(1) looks - does one a "period" carburetor ie a brass Stromberg

(2) application - a carb that might work well if one lives in flat southern Illinois will not work well where I live in the Missouri Ozarks.

(3) cost - yes, I know most will want the least expensive carb; but a carb that works well on a "parade" car might not give satisfactory service for touring.

(4) type of fuel delivery system - a carburetor that will work with the vacuum tank will NOT work with a pressure pump without modification.

We will hope the previous owner considered all of the above, and adjustment is all that is necessary. Once you know what he has, possibly one of you could give me a call (no obligation) to discuss the appicability of the current carb and its adjustment. 573-392-7378 (9-4 Mon-Tues central time).

Jon.

carbking,

Thanks. I am sure Tom will be in touch with you soon.

MCHinson here on Tom's Computer...

carbking,

Tom's carburetor is a Zenith # 4512900. From my limited research it appears that this carburetor was designed for an Allis Chalmers 153 Cubic Inch engine. That could explain why it runs lean. Tom will give you a call sometime soon.