Model Engine Maker
Supporting => Engine Ancillaries => Topic started by: Brian Rupnow on May 31, 2019, 12:25:14 AM
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The carburetors I show here are just about perfect for the 1" bore engines that I build. A-little story--It pays to shop around. I needed three carbs to replace ones I have stolen of old engines I have built to use on newer engines I have built. I checked on Amazon, and the price is $79 Canadian each. I checked with my local hobby shop and they said it was almost impossible to buy them now, but they could order two for $60 each. I then spoke with "Great Hobbies" and they said that these carbs were very hard to get now, but they could get me two for $49 each. I went back to my hobby shop here in Barrie and told them, and they dropped their price to $48 Canadian, each. It sure do help to shop around!!!
(https://imagizer.imageshack.com/img923/4729/p4AopG.jpg)
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That's a good deal Brian.
What makes these carbs so good for model engine use compared to yours & other folks designs? It seems that with the simplicity of a carb, just about "anything" with a needle & properly sized venturi would work. But we all know that's not the case...
Would it be worth it to take one apart, reverse engineer, & "" styleize" it for model engine use?
John
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John--I do build my own carburetors, but they are time consuming and I don't have the small machinery required to make some of the parts that these carburetors use. I have a 12" lathe and one of the largest tabletop mills. When you get down to the size of the parts in these carburetors, I can barely see them, let alone make them.
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John,
I'm with Brian on this one Pick your battles. I have built an Upshur single jet carb. The Upshur carb works fine, BUT, I have to adjust the jet to idle and again at full throttle. I made one of my own design based off a couple others, it was a failure. I replaced it with a Perry. About 5 years ago I bought the plans for Jerry Howell's 2 jet carb and am inclined to try that on the Upshur after some head modifications. On my Val I used an Associated .150 it looks very similar to the traxxas models Brian has there. Wonderful carb I maybe should have gotten one a little bigger, I'm guessing it tops out at around 6 grand. Seems like it should go faster but then again its a good governor. Building a good working carb is a big challenge.
Art
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That Traxxas carb comes from a 0.15 (2.5cc) 2-stroke, and there are many similar products (either 2-needle, tapered slot or slide carb) of similar or better quality available. I don't know if it's of interest, but I did a quick check and found (for example) the carbs from the ASP 15 and 21 are both available retail in the UK for under £17 (C$29) each*. There are many other examples. If you talked to a supplier like Just Engines and gave them an idea what sort of choke diameter you were looking for they could almost certainly recommend many options to choose from.
But do bear in mind that all these carbs (including the Traxxas) are intended for use with methanol-based fuels and while it may not be a problem for short, infrequent runs on petrol (especially if flushed through with alcohol solvent afterwards) it is quite likely that the internal o-rings used are not compatible with petrol-based fuels. When these carbs are used for spark-converted petrol engines in regular model flying the O-rings can tend to swell, turn sticky and/or start disintegrating. It is normal practice to replace the O-rings with ones of a different material - I can't remember the details, but I could find out of anyone wants to know.
PDR
* This excludes shipping, but includes VAT at 20% which you could probably not pay for an export order
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Allen--I use Naptha gas as a fuel in my engines, mixed with a small amount of 2 cycle engine oil to lubricate the piston/cylinder. I have been using these carbs for over 10 years now, and see no fuel related problems with any of these carburetors.---Brian
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I suspect that O-ring materials have improved in the last 20-30 years and when folks were using Methanol with glow plugs. As I understand it methanol was used because of the shortage of gasoline.
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As I understand it methanol was used because of the shortage of gasoline.
If you refer to model glow plug engines, then the answer is absolutely no - why - well the glow plug has an platinum wire that is a catalyst and methanol will keep it glowing and gasoline will not => a simple ignition system with methanol.
People and very big companies has been trying for decades to come up with a glow plug that works with gasoline and this was only solved about ten years ago when electric completely took over .... aka a solution that arrived too late.
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I know how you love a good story Brian: had one Sthil chainsaw and one Sthil leave blower get overlooked at the end of the season and the fuel wasn’t drained. The government mandated 10% Ethanol based gasoline here doesn’t react well to this. So, needed two new carbs. Went to the local dealer and was quoted $135 American doll hairs 8) each; dang near choked. Decided to sleep on it and decide whether to replace or repair. Thought I would check the old interweb and found them on Amazon for, are you ready, $ 15.99 each Prime, free second day delivery. Never know what is out there.
Whiskey
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Yup, I had similar experience with the genset (honda motor) carby - cheaper to buy a new aftermarket bolt-on carburetor on Amazon than to buy the rebuild kit.
FWIW, you can still buy no-alcohol gasoline in the USA, but you have to look for it. Most places that cater to power boaters will have it, and places with a lot of loggers around too. This website has a list of places in the US and Canada that carry no-ethanol gasoline, you can search by state/province:
https://www.pure-gas.org/
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Yup, I had similar experience with the genset (honda motor) carby - cheaper to buy a new aftermarket bolt-on carburetor on Amazon than to buy the rebuild kit.
FWIW, you can still buy no-alcohol gasoline in the USA, but you have to look for it. Most places that cater to power boaters will have it, and places with a lot of loggers around too. This website has a list of places in the US and Canada that carry no-ethanol gasoline, you can search by state/province:
https://www.pure-gas.org/
Hello Bent,
Thanks for this link.
Have a great day,
Thomas