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Briggs 18 HP Twin Carbs (2 versions?)
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Posted by pintopkp NY (My Page) on Mon, Nov 16, 09 at 9:07
| Hello all. I have a Briggs 18 HP Opposed Twin (422707-0135-01, Code 82111112) on an old Wizard GT I'm fixing up. It has, obviously, a carburetor on it; the kind with the fuel pump on the front of it and the two-piece carb body. Said carb was very dirty. While I was sifting through my many boxes of auction-bought parts, I found a carb that looked exactly like it. "Oh, boy" I thought. I can just stick this carb on (that was brand-new, by the way) and save myself a little trouble cleaning the old carb. Cool. So I bolted the new carb onto the engine, started her up, but she was running extremely rich and rough and smoking (the smoking being a bad head gasket I believe). After I shut her down, I could not start her up again and the new carb was flooding beyond all belief. To make a long story short, after tinkering with the new carb and comparing it to the old carb, I found two subtle differences:
1. The old carb has two screws, one looking like a high speed adjustment and the other, an idle adjustment. The new carb only has the idle adjustment, with a black hex plug where the high-speed screw would be.
2. The new carb has a nozzle in the throat of the carb coming from the "front" (the side of the carb with the pump on it) and the old carb has a nozzle coming from the side and further down in the carb throat.
Basically, my question is, are these two carb interchangalbe? I'm guessing the answer is "no" and that is what my engine wasn't running right. The strange thing is when I ordered the specified rebuild kit for the old carb, it only came with one replacement screw (for the idle) and not the other screw. I'm not an expert, but I know a little bit about small engines; I'm a little stumped here. Any help would be appreciated. Thanks in advance.
PS: I was about to take pictures too, but my cell phone battery died. If it will help more (which I'm sure it will), I'll add some pictures tonight. Thanks again. |
Follow-Up Postings:
RE: Briggs 18 HP Twin Carbs (2 versions?)
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| Pictures might help in identifying what you refer to as "nozzle". Also, reference the Briggs item # and part number from the IPL if you see the "nozzle" listed (thought Briggs might call it differently). Also, in regard to ***"After I shut her down, I could not start her up again and the new carb was flooding beyond all belief."***, your, "brand new, auction bought" carb may be missing the main jet, or the float, or needle valve. It is possible that the carb may have "donated" some of its innards to another carb during the time it spent at its former residence. |
Here is a link that might be useful: 422707 IPL
RE: Briggs 18 HP Twin Carbs (2 versions?)
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| In addition to what Mownie stated. I have a 20hp B&S twin, model 460777, code 9804215a which means mine is newer than yours and it also does not have the high speed adjusting screw in the front. The original engine for this Murray I had on it was blown. So when I began looking for another to replace, my mower parts guy, Steve, told me that my 15 hp twin was same block just different jetted carb. He told me to put the intake for the 20 on the 15 and I then had a 20. So from this long spiel, is that I remember the original 15 carb setup had the hi-speed adjustment screw where the 20 didn't. Ages were close, so maybe it has to do with the hp size for the variation. JUst my .2 worth. And you know a penny made at the mint today isn't worth a penny, so my .2 may not be worth much at all! |
RE: Briggs 18 HP Twin Carbs (2 versions?)
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| I just looked around on the outdoordistributors.com website. They have very good explanations of carb breakdowns. I found one that looks like the other two I have, although the innards are totally different. So, now that makes three totally different carbs that look the same on the outside. I'm beginning to think that my "new" carb is no good for my engine; will probably be added to my eBay lot soon. But I digress... I'll add some pictures and see what you guys think. Thanks for all the help so far! |
RE: Briggs 18 HP Twin Carbs (2 versions?) (w/pics now!)
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| So it was a little dark when I got home, but I did the best I could in the dim light of the shed. The first picture here is a top down view of the new carb, the one that I don't think I can use. Here is a view of the "nozzle" I was speaking of which is circled in red. In this view, the front of the carb (fuel pump part) is toward the bottom of the picture. 
Now in this picture, you can see the idle speed ajustment circled in red. The black hex plug (also in red) is where the high speed adjustment screw is on the carb that came on the engine. 
This next picutre is a top down view of the old carb i.e. the one that came on the engine. Again, the front fuel pump part of the carb is toward the bottom of the picture (so it can be compared easily to the picture of the new carb). The "nozzle" in this picture is circled in red again. You can see how it is in a totally different place than in the new carb (it kind of blends in with the throttle shaft, which I shaded blue). I already had the old carb apart to clean. 
And, finally, a picture of the old carb with the idle (first pic) and high speed (second pic). On this carb, there was a screw to adjust the high speed jet. 
Hopefully that paints a clearer picture. These seem to be totally different carbs.... Thanks again guys! |
RE: Briggs 18 HP Twin Carbs (2 versions?)
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| I should also mention that carb rebuild kits for this carb made by stens, Oregon, and Briggs no longer come with high speed needles/screws anymore. I had to buy one separately to replace the one on the old carb. |
RE: Briggs 18 HP Twin Carbs (2 versions?)
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RE: Briggs 18 HP Twin Carbs (2 versions?)
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***"Anyone?"***
Where shall I begin??
***"Basically, my question is, are these two carb interchangable? I'm guessing the answer is "no" and that is what my engine wasn't running right."***
Well, as an "off the shelf, ready-to-go" component that is EPA compliant, that auction bought carb "might not" be right for your engine, but if that carb was functional (not defective), it should still operate on your engine without drowning the engine with fuel. If the float, needle and seat are working right, no fuel will flow when the engine is not running. And if the carb main jet is in place, and of anything close to the appropriate orifice diameter (jet size), the engine should run and restart after shut down. So, have you inspected the "auction bought carb" to see if it has all its guts still in place?
At this point in the history of ICEs, carburetor size can pretty well be calculated by an engineer sitting in front of a computer. There is such a large data base to invoke (well over 100 years and counting) that hardly anything needs to be "re-invented" and so a carburetor can be selected from a big list of existing designs without having to do the "trial and error" method in such a big way. Of course, after choosing a carb for an engine, the engine will be tested under laboratory conditions to make certain that it operates well enough to go to market, and is compliant with EPA and other "standards". What does all the preceding have to do with the problem outlined in this thread?? Well, let's go a bit further down the information pathway. Many engine OEMs will use identical "base engines" in various different Horsepower output ratings, with only some minor changes of carburation. Sometimes the changes are nothing but a different jet size, but sometimes the difference will include a larger, or smaller, throat size in conjunction with diffent size jets. Now all that was just to sort of explain how marketing pressures and other concerns (like EPA standards) can affect which carb might be used on a given engine, but basically, a range of carbs can be used on various different engines in a "type and displacement group" and still be functional.
You are trying to use a carburetor of unknown origin and condition and have not gotten satisfactory results. That does not prove that the carb is unusable on this engine, but it might prove that this particular carb is defective.
I have basically the same engine as you (mine is 422707-0166-01) in a TSC Huskee. I will post some pictures of MY carb and we'll compare.
***"I should also mention that carb rebuild kits for this carb made by stens, Oregon, and Briggs no longer come with high speed needles/screws anymore. I had to buy one separately to replace the one on the old carb."***
I don't know if you wanted commentary on that or not, but here goes.
Because the adjustable main jet needle valve carbs are destined to fade into history, I would guess that the carb OEMs have decided not to furnish that needle valve with the gasket set any longer. Much better marketing strategy for them to just have a gasket set that fits ALL carbs of that series type than to toss in an unused needle too. This allows them to save a bundle on their end by not making a needle for every kit. And you can bet that any reduction in price of the kit without the needle can be measured in pennies on the consumer side, but in dollars on the manufacturer's side. And then, they can sell any needles at a premium price because applications calling for that part have placed it in a "niche market" instead of a "mass market".
Bottom line summary to this book of mine is: "If the auction bought carb is functional, it should not drown the engine like you describe. Also, if you believe this engine has a defective head gasket, you should address and correct that problem before attempting to do anything with the induction system. I'll get some pics. |
RE: Briggs 18 HP Twin Carbs (2 versions?)
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| I knew I could count on you for some great info, mownie! Thank you very much! I was thinking of that last night too; before I "experiment", if you will, with the two carbs, I'll replace the head gaskets and make sure I have some new plugs in there/have the combustion chambers nice and clean (just to be sure). I am looking forward to seeing pics of your carb though. You've got me very curious. Thanks again! I won't have a chance to play around with the engine again until this weekend probably, but I'll post back some results when I do, and, if I can figure it out, a video. |
RE: Briggs 18 HP Twin Carbs (2 versions?)
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RE: Briggs 18 HP Twin Carbs (2 versions?)
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| Thanks for the pictures, mownie. It does look like the same carb as my "new" one. If I have time this weekend, I'm going to change out head gaskets/plugs and then try the engine with each carb on it to see how it goes. I'll post back. Thanks again! |
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