zenith flooding

[larry harding]

my zenith carb is squirting gas out. here is what i have done .. cleaned and painted the cast body which is in good shape. put in the parts from a rebuild kit. put the float in a cup of gas, it bobs like a cork, no rattling or sloshing ,inside. tried one of the ball float valves, the float valve from the kit, and even the original one. i can hook the carb to my"i v tank"(an old lawn mower tank mounted on a pedistal i use to crank everything from motorcycles and scooters ,to hit and miss engines) with the carb on the table i can open the i v tank valve and in a few seconds gas is squirting up out of the jets. with the carb apart i can blow through the inlet and work the float valve by hand, works fine , but with the carb together the float wont close off the valve. i can turn the carb upside down and blow through the inlet and it is closed off, right side up, open. this thing is making me feel dumb. any suggestions???

[Fullraceflathead]

Maybe the gasket is just touching the edge of the float.

[Ed H.]

Something is holding the float down. As stated above make sure the gasket is not forcing the float down.
Try lowering the float, maybe it is set a tad too high for that carb.

[Mitch//pa]

Make sure the float does not have a worn spot that the needle gets caught on.. a common issue thats been posted before

[jimvette59]

I've had floats hit the side and hang up. JMHO

[larry harding]

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i'll do some more digging tomorrow, but this thing is really giving me a fit.
as i said i can turn the carb upside down and can't blow in the inlet right side up ...open. oh well i know when i do figure it out it will be something really simple and dumb that i am just missing.

[Gary WA]

jet length and gaskets for jets no gasket on idle jet. make sure old gaskets are out of jet areas. Last restorer had a great article on jets etc.

[Gary WA]

http://www.model-a.org/

[Tom Wesenberg]

Is the gas also coming out the vent hole at the seam?

[H. L. Chauvin]

Hi Larry,

1. The carburetor float valve is the only shut-off valve inside the carburetor to stop fuel overflow from a gravity fed "constant" fuel supply system such as that with a Model A.

2. Besides having the carburetor float level properly adjusted, a very old vintage proven method to check the "unseen" and extremely delicate Model A float up & down movement & the very light force required to close & open a float valve is to:

A. Assemble your carburetor, and while off of your car,

B. Hold your carburetor right-side-up by your ear ..... listen ..... and turn your carburetor upside down.

C. Sharp float clicks heard with right-side-up & upside down positions , means your float is working.

D. No click ...... you float is hanging up with float valve in the open or closed position.

E. If the float does not close the float shut-off valve with fuel being "constantly" fed by gravity your carburetor will leak like a thoroughbred stallion peeing after a 15 mile uphill horse race.

3. Most guys check the float's longitudinal side elevation position & movement.

4. Few guys check the floats transverse front elevation, alignment, & movement where a very slightly misaligned float can easily hit sides of carburetor or carburetor gasket and cease to cause the float valve to function properly.

5. Remember ...... dripping gasoline is more dangerous than horse pee.

[johnbuckley]

Originally Posted by Mitch//pa

Make sure the float does not have a worn spot that the needle gets caught on.. a common issue thats been posted before

x2
and also 1) check that the tag that is correct that prevents the float drooping down too far when fuel bowl empty is correct, if the float float hangs down at an acute angle too much it has problem floating up. When empty the float should reamain about 5 mm below valve and 2) check for friction on the hinge and pin.

[jhowes]

I had to convert 5mm to the English system and came up with 20 thousands of an inch. That's about the gap in a spark plug. Right?

[Tom Wesenberg]

5mm should be just a hair under 1/4". I'm looking at my ruler with inch on one side and mm on the other side.

[DaWizard]

Spark plug gap is .035 in, and to convert that to metric is .88mm.

Your 5mm is .196 in, way too wide for plug gap.

[100IH]

Is there a gasket under the needle and seat assy? Since you have tried 3 valves, try using a second gasket as a test - not a fix. This would/should provide a float level too low. Merely a diagnostic attempt to see what happens. I think I have seen thin shims for fine adjustments. Buy or make the external visible U tube gauge for fuel level measurements. Read John Buckleys #11 post carefully.

[H. L. Chauvin]

Hi Larry,

A. With your comment:

" put the float in a cup of gas, it bobs like a cork," could possibly give a false float test reading.

1. The old vintage "true" test was, first boil water in a small pot.

2. Totally submerge carburetor float in boiling water until water begins to boil again.

3. Reduce heat until water is resting calmly.

B. One can always be amazed to see the "heated" air within the float exiting a very tiny pin hole causing exiting bubbles almost as small as molecular size.

C. Vintage cars ran extremely well in the 1920's & 1930's because vintage mechanics had developed vintage common sense "true" methods to find problems.

D. Most mechanics today would swap out your carburetor and hand you a bill for same ...... volumes could be written on old vintage mechanical test from years ago ..... but ...... who cares today?

[larry harding]

finally got in the shop today to play with the carb some more. if i leave the gasket out it doesn't flood. i am wondering ... how is the float chamber vented?
with the gasket in place the chamber seems to be air tight. with no place for air to escape gas would be forced up out of the jets before the float could rise and stop flow. am i nuts or is there a float chamber vent some where i have missed? i seems like every carb i've ever worked on had some kind of float chamber vent.

[H. L. Chauvin]

With the gasket installed, per #10, do you hear the "click"?

[larry harding]

yep you can hear the float moving with the gasket in place. with the carb upright i can blow in a short piece of tubing and fitting i have in the gas inlet. if i turn the carb upside down i cant blow in, telling me the float is seating. i have two gaskets under the float valve, putting the float just a bit more than the 1' setting. i'm still wondering how air escapes the float chamber as it fills.

[DaWizard]

Originally Posted by larry harding

yep you can hear the float moving with the gasket in place. with the carb upright i can blow in a short piece of tubing and fitting i have in the gas inlet. if i turn the carb upside down i cant blow in, telling me the float is seating. i have two gaskets under the float valve, putting the float just a bit more than the 1' setting. i'm still wondering how air escapes the float chamber as it fills.

All the info I have seen about the Zenith 1 and 2 says the float should close at 5/8in from the top. Not sure what your 1in setting is.

[Dick Steinkamp]

Here's some good info and diagrams from Tom Endy.

http://www.modelabasics.com/Carb/ZenithPassageways.pdf

[larry harding]

just did a little trick... i used the old plug from the bottom of the carb. a little drilling, and some chainsaw/ weed eater fuel line( i've been changing several of those thanks to this crap gass we have now) and i have a fuel level guage. with the gasket out the gas filledl up about mid way on the bowl and stopped, with the gasket in place... same old flooding .
i just looked at the article, printed it out, and noticed a vent in the top over the bowl. i'm going to look for that vent hole. if it is plugged that is probably my trouble.

[larry harding]

after a little more checking i found a small hole right above the float hinge that
goes from the float chamber to the chamber in the middle of the carb that is open to outside air. that is the elusive/notorious vent i was hunting. you really have to be looking for it to see it. poked some rust out of the hole with a piece of wire and it looks like i'm on my way. thanks for the support guys!!!!

[H. L. Chauvin]

Hi larry,

Remember, none of us were born with several Model A carburetor repair toy kits in our crib.

Your not giving up should be admired.

Thanks for sharing your adventures.