Zenith Cab adjustment question

olut

olut

Member
Hi colleagues,

My 1929 Raodster Pickup runs well, it is all original, no modifications are made, except rear main with kork/neoprene, and that works perfect too...

...there is only one issue: engine attempts to stall at hard stopping. Now I know, it is related to too low fuel level inside the bowl. We tested this many times, if we would rise it by 2mm only, the cab ovefills, the current level is the best compromise.

The question now is, is this cab behavior typical for the Zenith ???

Greetings from Vienna/Austria

Albert
 
Hi Albert,

Engine is stalling is because of "too much" fuel in the carburetor bowl.

Ford recommended 5/8" from top of fuel to top of carburetor gasket at carburetor halves.

Please try readjusting carburetor float to reset fuel level 5/16" lower; i.e., 15/16" from top of fuel to top of carburetor gasket at carburetor halves.

Rex Reheis countered this Ford recommendation in his book & recommends same for A & B carburetors after years of experiencing carburetor rebuilding. I tried it & it worked for me.

----------------------------------------------------------------------------------------------

On another NOTE; no pun intended, when in a very quiet plush basement restaurant in beautiful Vienna with my son & his wife a few years ago, a violinist & an accordionist were quietly playing Strauss's waltzes whereby my son told the violinist that I played the violin.

The violinist handed me his violin, & the accordionist started playing "Home on the Range."

As he handed me his violin, I noticed everybody in the restaurant was looking at me.

Instead of "Home on the Range", I played the old fiddle tune & Roy Acuff's favorite , "The Wabash Cannon Ball", whereby the accordionist accompanied me smiling & never missing a note.

When we finished, everybody stood up, smiled, & clapped.

Until today, I think that good Austrian red wine made me do it.
 
H. L. Chauvin said:
Hi Albert,

Engine is stalling is because of "too much" fuel in the carburetor bowl.

Ford recommended 5/8" from top of fuel to top of carburetor gasket at carburetor halves.

Please try readjusting carburetor float to reset fuel level 5/16" lower; i.e., 15/16" from top of fuel to top of carburetor gasket at carburetor halves.

Rex Reheis countered this Ford recommendation in his book & recommends same for A & B carburetors after years of experiencing carburetor rebuilding. I tried it & it worked for me.

----------------------------------------------------------------------------------------------

On another NOTE; no pun intended, when in a very quiet plush basement restaurant in beautiful Vienna with my son & his wife a few years ago, a violinist & an accordionist were quietly playing Strauss's waltzes whereby my son told the violinist that I played the violin.

The violinist handed me his violin, & the accordionist started playing "Home on the Range."

As he handed me his violin, I noticed everybody in the restaurant was looking at me.

Instead of "Home on the Range", I played the old fiddle tune & Roy Acuff's favorite , "The Wabash Cannon Ball", whereby the accordionist accompanied me smiling & never missing a note.

When we finished, everybody stood up, smiled, & clapped.

Until today, I think that good Austrian red wine made me do it.
Click to expand...

-quite a story, HL...the Munich Oktoberfest is going on right now and I am sure you would be a hit there, replacing the "Take Me Home, Country Roads" song that Oktoberfest attendees seem so fond of. If you want to see a great rendition, search YouTube for "Wabash Cannonball" and watch it sung by the whole Grand Ole Opry company.
 
Thank you so much for your advise, I will follow it accordingly. Thank you for this nice story, indeed Vienna is a very cultural and romantic place :-)

Best Greetings
Albert
 
As a FYI, Zenith carbs that were used on an A would cause stalling issues on a hard stop, especially if going down hill. The issue is the gas moves forward in the bowl and there is none left to get into the jets on the rear side of the bowl. Raising the fuel a little may or may not help. Changing to a Tiltson X can help (complete different designed bowl), or a Model B carb as the bowl was redesigned.
 
Albert,

I agree with a couple of the above posts about the enjoyment of Vienna. Very nice city to visit and enjoy.

I had same problem with a Zenith I carb. I had reworked it with new parts and cleaned it but it still had problem. I then did notice that the float was not the 5/8 in. from the body. it seemed like it also was not level or parallel with the body. So I put another washer under the gas intake valve which raised the float and made it level. Worked fine after that! Hope this works for you. In fact, this is the best running carb I have.
 
jmeckel said:
As a FYI, Zenith carbs that were used on an A would cause stalling issues on a hard stop, especially if going down hill. The issue is the gas moves forward in the bowl and there is none left to get into the jets on the rear side of the bowl. Raising the fuel a little may or may not help. Changing to a Tiltson X can help (complete different designed bowl), or a Model B carb as the bowl was redesigned.
Click to expand...

Really ??, I wonder why in the four plus years of the Model "A" Ford never new that ??
 
Make sure you have the type 3 removable secondary well, the one with the undercut at the entrance of the compensating jet; also make sure the compensating jet is not too long and blocking the fuel entering the removable secondary well. the pickup tube on the idle jet is located in the center of the removable secondary well, sounds like you are running out of fuel to the idle jet. Also check the idle air adjustment screw to be sure, when turned in all the way, it closes off all air ? often times the needle end is too short and you loose control of air to fuel ratio; when working properly 1-1/2 turns open should get you in the ball park and then fine tune for smooth running.

Ron
 
Never had that problem, Zenith carb works great. I think you are mistaken.

Fred K-OR said:
Albert,

I agree with a couple of the above posts about the enjoyment of Vienna. Very nice city to visit and enjoy.

I had same problem with a Zenith I carb. I had reworked it with new parts and cleaned it but it still had problem. I then did notice that the float was not the 5/8 in. from the body. it seemed like it also was not level or parallel with the body. So I put another washer under the gas intake valve which raised the float and made it level. Worked fine after that! Hope this works for you. In fact, this is the best running carb I have.
Click to expand...
 
Hi Albert,

FWIW:

Mr. Rex Reheis mentioned in his book that he did not think that when a Model A vehicle stopped suddenly, that the engine's stopping was caused by the often mentioned myth of fuel starvation.

If this were the case, one would want more fuel in the carburetor bowl to prevent this fuel starvation phenomena from occurring.

On the other hand, his theory was that the high level of fuel rushed forward, then the fuel sloshed backwards & pushed excess fuel in the fuel inlet; hence, this excess fuel caused the engine to become flooded on sudden stops.

So in order to prevent the engine from flooding on sudden stops,, he recommended "lowering" the recommended fuel level in the carburetor from 5/8" to 15/16".

If you notice in Model A Zenith carburetor diagrams, (as Mr. Reheis also states in his book), fuel is withdrawn from the small hole in the "bottom" of the carburetor bowl; hence, as he states, if one "lowers" the fuel level, fuel can still be always withdrawn from the bottom of the bowl & fuel "starvation" will not occur.

Years ago, I had always used a Sears Marvel carburetor on my Model A & never experienced the engine stopping on sudden stops like with that of a Zenith.

Hope this helps.
 
H.L. I think your comments are right on. In thinking about my experience of putting in another washer under the fuel valve, it did lower the amount of gas in the carb and stopped the problem of turning off the engine with a quick stop.
 
Albert,
This is just a typical Model A/Zenith "QUIRK"! When stopping FAST, just pull your throttle lever down 2 or 3 clicks & problem solved!
Some say they found "cures" for it, I wonder if they have really good holding brakes or not???
If this sounds "smart assed", The Dog:cool: is NARRATING!:D
Bill W.
 
Bill, in the case of my carb, it was a "cure". I had been fighting this problem for a year or so and I had almost given up on it. I did do like you mentioned, pulled the throttle down, etc. for a long time and got tired of doing that. So I put in the washer under the gas input valve and now I can slam on the brakes and it stays running.

Maybe it is the luck of someone like me who does not know much about this sort of thing and just stumbles onto something that works based on all the good advise received from the Barn
 
Hi Fred,

Adding washers as you mentioned is how Mr. Rex recommends float adjustment to lower the fuel level in a Model A carburetor; however, on the Mode B carburetor he recommends bending the float tang in lieu of adding washers.

Sometimes overlooked he also mentions, is if one sets fuel height by measuring the height of the float seam when the carburetor top half is turned upside down, is important to observe if the float seam is level when also looking at the float from the front end, perpendicular to the side view, which can naturally affect the fuel level.
 
Thank You all for your kind input, I got an offer from an expert in the UK to fine tune the cab, so I am going to buy one from MACs and will send it to the UK, I was told, that in many cases, the new cab are fitted with wrong jets and wrong adjustments. I am tired to take the cab off for adjustments for so many times. Once the new one works on my car, the old cab will be send to the expert, for same cure.
Meanwhile I use double pedal technology from Rally sports to avoid stalling. By the way, "hard stopping" is a nice expression to describe the loosing of speed when initiated... :-)

Cheers from Vienna
Albert
 
Fred K-OR said:
Bill, in the case of my carb, it was a "cure". I had been fighting this problem for a year or so and I had almost given up on it. I did do like you mentioned, pulled the throttle down, etc. for a long time and got tired of doing that. So I put in the washer under the gas input valve and now I can slam on the brakes and it stays running.

Maybe it is the luck of someone like me who does not know much about this sort of thing and just stumbles onto something that works based on all the good advise received from the Barn
Click to expand...
Fred,
I'm tickled that you found that "perfect" float level spot!! Persistence paid off for you. When Vermin's running, I'll see how his Zenith operates. I also have a perfect Tillotson that I "loaned" to a friend & FINALLY got it back when he sold the car. He said, "DON'T even diddle with, it runs perfect":D I want to compare the performance with each carb, as I have NEVER ran a Tillotson in the past.
Bill W.
 
One more silly questions:

The knop on passenger side to adjust air/fuel mixture is set 1/4 turn anti clockwise from closed. When I open it further anti clockwise I don't recognize changes. I understand that turning anti clockwise mixture become rich, turning it clockwise it will become lean.

I also checked the coupling at the carb, it is locked, so no free spin.

...is this normal, mixture knob should be open for one and a quarter turn anti clockwise?..".

Cheers

Albert
 
Is it realy the opposite?

The needle closed, turned clockwise till the end is rich ?

The needle open, turned anti clockwise, for example one turn and a half is lean?

Please confirm

Thank you

PS: I neve touched this, kept it as I got it...
 
the air bleed screw on the carb clockwise is rich counter clockwise is lean

the gav inside the passenger compartment clockwise is lean and counter clockwise is rich
 
You must log in or register to reply here.
Back
Top