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OS 46 FX - Part needed

Old 02-10-2020, 11:37 PM
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hsanchez
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Default OS 46 FX - Part needed

Good Evening. I crashed a plane at my club's field during this past weekend, and the plane was totaled. I had an OS 46 FX in the plane, and the engine appeared to have survived for the most part...with one big exception. This particular model has the needle valve mounted on an appendage to the back plate, and the appendage was broken off from the back plate in the crash. I checked on the website for the prime retailer for the engine, but I could not find the back plate, so I am assuming that it is no longer available. I have heard some horror stories about attempts to use compounds such as JB Weld to re-attach the appendage, in which the compound ultimately failed. Has anyone out there any suggestions about where I can find a replacement back plate for this particular engine? Any advice here would be appreciated.

Thanks,
Harry Sanchez
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Old 02-11-2020, 05:54 AM
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Propworn
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Originally Posted by hsanchez View Post
Good Evening. I crashed a plane at my club's field during this past weekend, and the plane was totaled. I had an OS 46 FX in the plane, and the engine appeared to have survived for the most part...with one big exception. This particular model has the needle valve mounted on an appendage to the back plate, and the appendage was broken off from the back plate in the crash. I checked on the website for the prime retailer for the engine, but I could not find the back plate, so I am assuming that it is no longer available. I have heard some horror stories about attempts to use compounds such as JB Weld to re-attach the appendage, in which the compound ultimately failed. Has anyone out there any suggestions about where I can find a replacement back plate for this particular engine? Any advice here would be appreciated.

Thanks,
Harry Sanchez
[email protected]

OS stopped making the cast needle valve lug because they broke easily. Its a good thing they usually broke leaving the hole on the backplate intact so you could file and shape the backplate so you could still use the four screws to seal it. They replaced it with a stamped steel bracket and a new needle valve that worked better. I believe you can replace these with the ones from a 46 AX

Last edited by Propworn; 02-11-2020 at 05:56 AM.
Old 02-11-2020, 11:07 AM
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rgburrill
 
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I'm surprised a JB Weld failed. I used it on a carburetor mount once and that gets a lot of heat. It worked for a long time, longer than the cylinder itself which was destroyed in a nose in crash into a paved runway.
Old 02-11-2020, 11:54 AM
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My FX has a sheet metal bracket attached to the backplate, but I have repaired many plastic LA ones by making new brackets, or drilling a 1/16" hole in the remaining boss of the backplate and holding the needle assembly on with a tie wrap. It depends on the app and how much meat is left. Often the plastic backplate takes the whole corner out which destroys the whole backplate, but the needle assembly can be salvaged for something else. I use one on my test stand. There is often a redneck way to do something.

Old 02-16-2020, 04:59 AM
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You don’t want the needle valve mounted to the engine anyway - it’s too easy to have nucleation bubbles show up (from vibration) that can cause all sorts of tractability problems. Mount the needle valve on the same plane as the engine (close/even with the carb) and reasonably close to the carb. This ensures adjustments are accurate. Too far away and the engine can respond slower and end up being too lean. If you’re using a bubble less fuel tank, then mounting to the engine is fine.
Old 02-16-2020, 05:39 AM
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Propworn
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Well just about every glo engine has the needle valve attached to the engine and they run just fine. No need to over complicate it.
Old 02-16-2020, 07:39 AM
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And how many threads are there of people’s engines quitting in flight and when they move the needle valves off the engine they run fine.

I guess if all you run is pedestrian OS engines, you may or may not encounter nucleation bubbles between the carb and remote needle. If you step up to something more powerful (with more vibration), then you may see the light. But I’m not judging.
Old 02-16-2020, 04:52 PM
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DUHHHHHH Can I explain it to you slowly??????? HE...................................IS........... .............................RUNNING.............. .....................AN........................... .................OS............................... ..........ENGINE............................NO.... .................NEED............................. .........TO....................................... .......COMPLICATE................................. ..............IT!!!!!!!!!!!!!!!!!!!!!!!!!!

Old 02-16-2020, 07:23 PM
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Listen, Richard, I’m just saying it’s a good thing that needle holder broke off. Nothing complicated about that.

richard.
Old 03-31-2020, 07:21 AM
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Hi Harry.
Part number is 25607000 and maybe someone near to you have it in stock or ebay etc. Try to google and maybe you get lucky.
In my country I can see the part is listed as still available at my local hobbyshop.
Troels
Old 03-31-2020, 07:54 AM
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Very common problem. If the backplate still seals completely (no cracks, gaps, etc.) there is no issue using the needle valve "loose" in line and/or even more remotely. But it will flop around, making it hard to grab to adjust, and perhaps banging around on stuff. It can be a long ways from the engine, and still do its job. Depending on the situation, I've used zip ties to hold it down, made wood or aluminum brackets to hold it, even mounted it on the firewall. Depends on how much of the original bracket you may or may not have (and feel like reusing), what scrap materials you have around, how creative you are, and the particulars of the plane you will be putting it in. But, no mechanical reason it has to be remounted where it was.
Old 04-05-2020, 06:41 PM
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I say buy a 46AX carb and put that on the FX

then take the FX carb and put it in a vice that is mounted on a milling machine bed and start milling the FX carb until it is completely gone, but that's just what I would do <oops, edit, that's what I would do for my 61FX carb

Jim

Last edited by the Wasp; 04-05-2020 at 06:45 PM.
Old 04-05-2020, 06:57 PM
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https://www.towerhobbies.com/cgi-bin...?I=LXGCV3&P=ML

https://www.horizonhobby.com/SearchDisplay?
searchTerm=needle+valve+assembly&categoryId=&sourceDomain=&storeId=10151&catalogId=10051&langId=-1&pageSize=40&beginIndex=0&sType=SimpleSearch&resultCatEntryType=2&searchTermScope=2&showResultsPage=true&searchSource=Q&sourceDomain=&pageView=


https://www.towerhobbies.com/cgi-bin...alves+assembly

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