Carburetor mating surfaces

W

WallaceHardware

Junior Member
Hello, my name is Tyler, I work at Wallace Hardware in OCNJ, and here in our store, we have a 1929 ford model a pickup that has been with the store for nearly 80 years. The truck had not run in around 4 to 5 years, and a few months ago, me and a coworker began tinkering with it to get it to fire up. We replaced the rotor, ignition coil, plugs, and plug connectors. After this and a decent amount of starting fluid, the truck ran on it's own, but we noticed that it was leaking fuel from the carburetor, so we proceeded to order a rebuild kit and remove it. Yesterday we began the process of reassembling the carburetor. While we were putting it back together, I noticed that the two major halves of the carburetor did not meet flush when reassembled. I looked at the new seal/gasket that was sent with it, and it was slightly thinner than the previous one that was removed, but there were major gaps when attempting to reassemble it, and it got to a point where I realized that it simply was not going back together at that moment. My question is, are most of these carbs like this due to the machinery in 1929 not being very exact, or has my carb been warped and I need a new one? If I don't need a new one, how do I go about filling these gaps where the 2 halves meet, they were about 3 mm. Thank you to anyone who can help
 
Hello Wallace Would two gaskets fill the void or with a straight edge find what surface top or bottom you need to replace or resurface.
 
Good morning Tyler. First off, let us know what brand carburetor we are dealing with. This will help with the suggestions.

Some of the carburetors are more prone to warpage than others. You may have to flaten the mating surfaces using a flat surface (a piece of glass works well) and a sheet of sand paper. I would assume a hardware store would have both?

On my Marvel Sheblers I cut my own gaskets using Cork/Buta-N. The cork is much softer and conforms better than the paper gaskets you get in a kit.

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WallaceHardware said:
Tilliston(I hope I spelled that right) model X
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A Tillotson is made of zinc and is prone to warpage. I would not use two gaskets. Try flattening the surfaces first. DO NOT over tighten the screws as this will worsen the warpage (and probably contributed to the problem in the first place).

Check and flatten the carb to manifold flange also. Know area vacuum leak.
 
We do have glass and I have checked the one side opposite from the one with the float attached and it is most definitely not flat, I cannot easily check the other side as there is a fixed piece that protrudes from the mating surface, but how would I go about resurfacing these pieces?
 
that too is warped, checked it yesterday, so should I get a new carb or resurface the one I have, and if I keep it, how do I resurface it.
 
WallaceHardware said:
We do have glass and I have checked the one side opposite from the one with the float attached and it is most definitely not flat, I cannot easily check the other side as there is a fixed piece that protrudes from the mating surface, but how would I go about resurfacing these pieces?
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See post#3. For the side with the protrusion use a small flat file.

Some people in the past have suggested to put a clamp on the carb and heat it in an oven (hopefully when your CEO isn't home). I have not tried this. Maybe someone who has will chime in.
 
The only issue I see with this, is that the piece where it doesn't meet is raised, which means I would have file everything else on the carb but the spots where it doesn't meet. That seems like a lot of time and a lot of room to royally mess something up
 
WallaceHardware said:
The only issue I see with this, is that the piece where it doesn't meet is raised, which means I would have file everything else on the carb but the spots where it doesn't meet. That seems like a lot of time and a lot of room to royally mess something up
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The easiest solution might be to put it in the oven as Y-Blockhead suggested in post #9 above and use a clamp on the raised part. Make sure there is no gas in carb before you do so!

David Serrano
 
It might be easier to find another aftermarket carb like that or get a rebuilt original and never have the problem again.
 
when one starts in this hobby- the worst thing is to hit a wall on such a common issue and lose interest..........


better to get another carb and go and drive the truck and have some fun!
there will still be plenty of repairs to be made.
 
I too suggest getting a "new" carburetor. My personal preference would to go away from the after market Tilliston and go with a Zenith. Burt's Model A along with other Model A vendors can set you up with one ready to bolt on.
 
Just sitting the carb should not leak fuel even with the warpage issue. It probably means your float valve is not shutting the flow of fuel to the bowl and it is overfilling. Just make sure if you fix the warpage that you also check this valve as it needs to operate properly to stop the fuel leaking.

Jerry
 
Jerry Kzoo said:
Just sitting the carb should not leak fuel even with the warpage issue. It probably means your float valve is not shutting the flow of fuel to the bowl and it is overfilling. Just make sure if you fix the warpage that you also check this valve as it needs to operate properly to stop the fuel leaking.

Jerry
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Good point Jerry. Also check that the float is not set too high.
 
My pickup came to me with a Tillotson, and indeed the top and bottom halves do not mate properly - more than 0.025" gap. It appears that the warp is in the top half. For now it's running OK, so I'm not inclined to mess with it too much, but I have a bunch of Zeniths around and I'll eventually get around to building one good one and installing it. (Tyler, for your background, the Model A came with a Zenith carburetor. The Tillotson was a popular aftermarket replacement. If adjusted properly, the Zenith is a fine and very robust part. I don't expect that today many of us here on the forum would preferentially install a Tillotson over a properly functioning Zenith. If you elect to replace the one you have, 1crosscut had a great idea to contact Steve Becker at Bert's Model A Center in Colorado, he can set you up.)

I've had success with flattening mating surfaces by taking a granite plate (or a piece of thick plate glass), attaching a piece of 220 grit wet-or-dry to it, and gently moving the part across the paper. Rotate the part 90 degrees about every ten strokes or so. Don't press down hard on the part or you will unconsciously slant the surface - it may be flat but not necessarily aligned properly. I do this as a matter of course to things like goosenecks, carb upper mounting surfaces (to the manifold), etc. It's difficult to do with upper carb bodies because of the things that protrude down like the float mounting bracket.

For parts that are too big to move (like the upper gooseneck mounting surface or water pump mounting surface on the head) you can use a large sharpening stone, available at most hardware stores.

I agree with Jerry Kzoo and Y-B, though, that if you're pouring gas out then you have a float height adjustment issue as well as a mating surface issue. The float height adjustment issue is the more critical at this point and needs to be solved first. Good for you that you're diving in to try to solve this, that's how you learn.



JayJay
 
Tyler, all the above is good info. If CEO denies oven use or wallet dictates a cheaper bodge then consider loctite 5800 ( or maybe build up mating surface with loctite 3090) if you have those products in the USA.
 
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