3D Printing A Carburetor Is Easier Than You Probably Think

We’ve all been there. You see a cool gadget on the Internet to 3D print and you can’t wait to fire up the old printer. Then you realize it will take 8 different prints over a span of 60 hours, chemical post-processing, drilling, exotic hardware, and paint to get the final result. [Peter Holderith’s] carburetor design, however, looks super easy.

If you have experience with real-world carbs, you might wonder how that would work, but as [Peter] points out, carburetors are very simple at the core — nothing more than a venturi. All the extra pieces you think of are for special cases and not necessary for basic operation. We doubt, though, that you could really use the thing in its current form in your car. There are no mounts and since he printed it in PLA, it seems like a hot engine would be a bad idea. However, it does work well with water and an electric blower.

[Peter] mentions that with some more work and the right material, he has no doubt he could create a working practical carb. We think he’s right. But even in this form, it is a great educational project for a budding car enthusiast — like the old transparent V8 engine models, maybe.

Speaking of transparent, we’ve seen — or maybe not seen is a better phrase — a see-through carburetor that is also a good demonstrator. If you could perfect a 3D printed carb, it would make conversion projects a lot easier.

27 thoughts on “3D Printing A Carburetor Is Easier Than You Probably Think

  1. Years ago, at a vintage vehicle rally, a friend of mine bought an old Villiers 2-stroke motorcycle engine in the autojumble.

    We were there for a few days, and he really wanted to know if the engine would run, but it had no carburettor.

    So, he whittled a carburettor out of a bit of tree branch and some fuel delivery hose, and the engine did, indeed, run.

    The article is right, carburettors are, in essence, very simple.

    1. My cousin had an opel corsa that was in a no start condition. being efi we had no idea where to start in repairs.

      along came an elderly friend who poured out a bottle cap of petrol and while we cranked over the engine, he spilled it into the intake maniford, and it ran for a few seconds, leading us to the diagnosis that the engine and computer was fine and the fuel pump was at fault.

      I was amazed at this at the time because i thought carbs were too complex to emulate like this.

      I think the above carb will likely run but won’t idle

      1. I’ve done something similar but with propane. It’s surprisingly easy to run small engines with only a valve and hose running into the intake.
        I lost the float pin to my pressure washer a while ago and ran it like this for a week until the new part came in. Oil stayed super clean too.

        1. I have done the same thing with propane to run small engines.. even ran my car that way once when the fuel pump died.. I stuck a propane hose into the intake and just regulated it with a ball valve with the tank on the passenger seat :-)… This article gets me thinking of making a propane conversion for a generator.. should be fairly easy and be way cheaper than the many hundreds of dollars they want for a conversion kit.

          1. Do it! It’s so nice not worrying about bad gas and carburetor crud. I’ve got a demand regulator and the fittings to convert my riding mower this summer. I get a ton of those free small camping bottles and I’m eager to see how long one will last.

      2. Yep, keep a can of starting fluid around for just such diagnosis. If it coughs or starts on the fluid, you have a fuel system problem not an ignition problem.

      3. The motor is a pump also, so you can block the air intake fully with your hand or something and pull enough fuel through to fire it… Doing it this way has the advantage that if the jets or needle valve got a bit gummy or gunky it could have pulled it through and it will run fine afterward. If it cuts out again then the things that are supplying fuel are needing investigation of course. For later cars, suspect fuel filter clogging if it’s been a while since it had a new one.

        1. I have a tendency to start ancient lawn equipment by this method by default.. the thing there would be that the primer bulb is likely rock hard and/or fragile, so it don’t take a moment to spin that big old panhead bolt off to pull the filter, can do it with a thumbnail often, or a coin or a key if it’s real stiff, then give it two slow pulls with your hand clamped over to prime it, stick the air filter back on… good hard pull and it starts “first try”… though IDK if improving your chances like that qualify for “first try” but most of the time it works.

        2. I think that blocking the inlet will only suck fuel from the tank to the carb if the jets are bigger than the carb bowl vent. And I don’t think that is generally the case.

          1. Well it works on Webers, Zenith, Solex and SUs… but.. I guess you wouldn’t notice it not working unless the float bowl was bone dry.

  2. The title needs to be changed to: 3D printing a carburetor is probably easier than you think – the way it is now – it implies that you might not even be thinking at all

  3. I literally segued recently from a 3D part print offer as-is by a nice young lady who thinks she’s old, then thinking as a lost PLA casting method, then electroplating the 3D print (Husquvarna Viking crank slide) potentially to make better quality cost effectively (possibly graphite ink, then copper then nickel/chrome) in a messy way (I know machining is easier)… to electroplating one of my carb bowels at least and possibly the float… to now wondering if one can 3D print the whole carb and electroplate for better quality performance. Interesting thoughts over the last month or so. I think I have all the gear now and will see when I can move beyond thoughts.

    1. Seems like the challenge is going to be finding a material that will survive the heat cycling and fuel itself. It should be a really smooth print for proper flow. I suppose I would maybe try a plastic prototype to prove it worked and then farm it out for SLS metal printing. Of course, that might all be more expensive than adapting an off the shelf available carb.

      1. There’s been a little on Hackaday and Youtube noting using PETG (I’m guessing pulltrusion PET from recycled bottles would perform even better) for carb intakes for like the lawnmower carb powered 302 Maverick, as well another YTuber the_eddies demonstrating 3D printing intake gaskets using another material.

    2. Yeah there was a kind of Victorian age 3D printing thing called “electrotyping” where they’d graphite coat a master and plate the heck out of it, until they had a metal copy. Wax or plastic you could then melt out if you wanted, if it wasn’t two halves you could remove plug and solder, braze or weld back together.

      I think it’s an under-used technique that would be well suited to making metal parts with 3D printed molds, forms, plugs, whatever you wanna call them.

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