Model B Carb issues

[AL in NY]

I don't the removable venturi. Either it not pictured or you don't have one.

[KMeredith87]

Sorry, forgot about that! I do have one and it has been in but it's not pictured.

[TDO]

FAR AS THE FLOAT LEVEL, I SET MY B FLOAT SAME AS THE A FLOAT. Mine runs great.

[1930artdeco]

I have run a B carb on my car just like yours, original jets etc. I however, do not have the brass shim that you have under the float. Sounds like your float is good, try removing that shim. It may be binding the float up.

Mike

[AL in NY]

I agree with 1930artdeco, try removing the baffle under the float. When I first installed my Zeinth B, I couldn't get it to work reliably with the baffle installed.

[tbirdtbird]

Sponsored Links (Register now to hide all advertisements)

starving for gas.
check GAV circuit carefully

[AL in NY]

As I said in post #8, the pressed in GAV needs to be removed because the spring and the washer under it tend to rust. And because of the spring, that area is almost impossible to clean if rust is present.

[KMeredith87]

I haven't had the chance to remove the shim and give it a shot yet but that will be one of the next test.

AL, I don't have the proper tools to remove and reinstall the GAV circuit. Any suggestions on how to possibly remove the. And reinstall without messing it up? I actually do have a new spring and washer for it but no way to install. What about filling the bowl with evaporust?

[Purdy Swoft]

Artdeco makes a good point in post #46 . I don't run the lower shim in my B carbs. Another possibility that I don't think has been mentioned is the possibility that the needle valve could be sticking. I've had problems with viton tipped needles sticking closed. Ethanol fuel contributes to this problem. I notice that the high speed jet that presses into the upper housing is missing. Without the high speed jet, the B carb would probably not perform much if any better than a model A Zenith carb. I've made this jet by turning the nut off a model A idle jet and shorting the tube to proper length. The diameter is the same.

[KMeredith87]

Purdy, the power jet is there, it's a stainless replacement tube instead of the brass. I'll try removing the shim for sure but right now it sounds like a May be having a problem in the GAV circut. My needle valve is actually an original I took apart and polished for a tight seal and seems to be working fine right now. I too have had problems with the viton seals and won't use them anymore, not worth the hassle to me.

[Purdy Swoft]

Sorry, I see it now. Don't know how I missed it.

[Ron in Quincy]

Unless you are running a fuel pump, the baffle and spring are not necessary. The baffle and spring only appear on the 33-34 B carbs; the 32 B carb uses a round float with no baffle and spring.

Ron

Another way to identify a 33-34 lower bowl is a cast baffle in the bowl 11/16" down from the mounting surface on the passenger side of the bowl.

[AL in NY]

To make the puller for the dash-controlled needle housing you need to obtain a 1/4 x 24 die. You won't find it at your local hardware store but industrial supply houses carry them. That's the thread on the GAV adjusting needle. Kmeredith87, I think you would be wise to purchase a copy of Gordon Biggars book "Restoring The Model "A" and "B" Carburetor - The "Rex" Reheis Way". I saw your earlier post on not being able to find the correct bass plugs, so you didn't remove them for your rebuild. Biggars books tells you how to fabricate plugs. But there is another way. You can drill and tap the plug holes and then insert set screws with a thread sealer applied. You are not building a fine point car, so who cares what the plugs are made from if the carburetor functions correctly after it's rebuilt.

[Giles]

Originally Posted by AL in NY

There is a removable brass plug in the upper housing that has a vertical slit in it that is open to the throat of the carburetor. Careful tap it inward until it falls out and check the top of the idle passage under this plug for rust and dirt...

Hi Al, and everyone,

I have just removed and cleaned this plug in my model B carb. I noticed that as well as having the vertical slit and a passage drilled sideways through the plug, there is a tiny hole on the outside end of the plug (ie opposite end to the slit). This does NOT, however go all the way in till it meets the crossways hole. It is not blocked - it clearly never went all the way.

My question is simply: should this hole meet the crossways one? (In other words, have I got a faulty plug?) If it doesn't, what is it there for, since it doesn't connect with anything?

Thoughts, anyone?

Best wishes and thanks, Giles

[AL in NY]

Giles, I believe that "hole" is just a punch mark and it doesn't go through to the vertical passage.

[Giles]

thanks Al - now I can relax!

[JRN1967]

Originally Posted by AL in NY

There is a removable brass plug in the upper housing that has a vertical slit in it that is open to the throat of the carburetor. Careful tap it inward until it falls out and check the top of the idle passage under this plug for rust and dirt. Also, under the GAV is prone to rust also and the GAV is pressed into the lower body of the carburetor. If you haven't removed to GAV totally, the engine will never run right.

Al, This winter I bought a rebuild kit for my B carb. When I installed the carb it ran like it was starving for gas. It also stalled at quick stops, which exactly what it was designed not to do.

I tried adjusting the float level many times and removed the baffle. I put it on the shelf and almost forgot about it. Then I picked up a 31 Sport Coupe that was missing the carb (and some other parts), so I needed to get this carb working. Through a search I stumbled onto your suggestion here about removing the brass plug with the vertical slit.

I just wanted to say thanks, because now the B carb runs great. It's so good that I'm going to put it on my driver.

John

[rich40701]

When the brass plug with the vertical slit is tapped do you leave it out. I have had the B carburetor on my A on and off 3 or 4 times now and it starts really easy but the idle is very erratic. One minute it will be idling great and the next it won't idle unless you increase throttle. Additionally when I first put new jets in it seemed to have more power but leaked fuel so I took it back apart and adjusted the float and took all the jets out to make sure nothing was leaking. After I put it back together I still have poor and erratic idle but now loosing power at top end. The only good thing is it no longer leaks gas.

[RENNERS CORNER]

I make all the plugs for the model B Zenith but that's ridiculous to drill them out if the passages check good with compressed air there is absolutely no reason to drill those plugs.
When they were brand new they operated perfectly, jets are not the reason for your issues.
Over the years people have mixed matched parts you cannot mix parts from the B1 zenith and the B2 zenith without knowing what you are doing. See photo attached of throttle plate with notch as an example of a part that you cannot enter change.
I have attached diagrams for the model A & B Zeniths and a checklist for going through all of the passages and circuits with a rubber tipped blow gun.

[RENNERS CORNER]

The hole on the outside of the plug on the outside of the carburetor was a manufacturing hole for orienting the plug so the slot was straight up and down. That plug is called an idle aperture and that's where all of your fuel for the idle circuit enters the throttle bore.