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Old Dec 12, 2014, 03:07 PM
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Royal os 40 exhaust

I have a Royal os 40 engine, i have to extend the exhaust 3" does anyone have an adapter for this.? or know where i can get one? also I need 3" long socket head screws for the same engine, and does anyone know what size those screws are.? thanks for reading this and helping.
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Old Dec 12, 2014, 03:42 PM
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Irrespective of the replies you get to your question, most of which will be very helpful. I suggest the following. Take your engine to an industrial screw supplier. Here you will be able to determine the exact size and length of the appropriate screws for your engine.

I cannot help you with the adapter.

Regards,

Ed s
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Old Dec 12, 2014, 03:42 PM
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royal or OS? these are two different brands....pretty sure royal only "made" a .46 and not a .40 while OS has a few different models of .40 size engines with different exhaust mounting patterns.

screws are going to be M3 or maybe but most likely not M3.5 and 3" long ones might be hard to come by.

you might find something that works here: http://www.macspro.com/prodline.asp
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Old Dec 12, 2014, 04:53 PM
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I made a couple of very long bolts with steel rods, sort of like "all thread" rods, by tapping threads on each end, and using nuts and washers.

I have access to old electric motors for small fans, etc, and some of those bolts are 3-1/2 " long, but need to be tapped to the correct pitch.....These are mostly S.A.E., not metric, however.
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Old Dec 12, 2014, 06:34 PM
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http://shop.dubro.com/c/aircraft_muffler-accessories I had/have one of these. Can't find it right now to check for fit, but think it would work. It only has the big square hole. You would need a drill press or mill to get the bolt holes in.
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Old Dec 12, 2014, 09:01 PM
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Quote:
Originally Posted by ZAGNUT View Post
royal or OS? these are two different brands....pretty sure royal only "made" a .46 and not a .40 while OS has a few different models of .40 size engines with different exhaust mounting patterns.

screws are going to be M3 or maybe but most likely not M3.5 and 3" long ones might be hard to come by.

you might find something that works here: http://www.macspro.com/prodline.asp
They also had a .40 during the 80's, it was kind of a copy of the OS 40 FSR. Some details here:
http://www.rcgroups.com/forums/showthread.php?t=1292531
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Old Dec 12, 2014, 10:31 PM
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My Royal .46 has M3 x 30mm muffler bolts. It looks identical to my .46 LEO except for the remote needle on the LEO. They seem to run ok, I have not put them on a plane yet.
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Old Dec 12, 2014, 10:52 PM
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If you have a local store which caters to the R/C car group, sometimes they will have M3 and M3.5 products (and other sizes) in the length you want. You might check with them.
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Old Dec 13, 2014, 12:29 AM
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http://www.mcmaster.com/#
IF they don't have it,it ain't made.
They will list in a way that you might find confusing, first by diameter, then thread pitch. Not sure what those pitches would be, I don't use metric. But for aluminum, as in the muffler or the block, the fine pitches won't be it. DIN is the standard used in Europe, JIS is Japan Industrial Standards, which even the japanese don't use anymore. SAE is Standard of American Engineering. Safest way take the thing to any machine shop that does jobbing or repair work, they'll tell you in less than half a minute. Might have the bolts too.
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Old Dec 13, 2014, 09:30 AM
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at mcmaster you probably won't find any kind of M3 screw over 60mm in length. all thread and nuts is the solution.

pretty sure they don't do M3.5 either, those are really hard to find even though they seemed to be the standard screw size on just about all .60 size engines.
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Old Dec 13, 2014, 09:36 AM
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McMaster doesn't have any .60 metric pitch screws either. At least not in the M2.5/M3/M3.5 sizes. I have some Enya .15's that have .60 pitch JIS screws that got all buggered up by the previous owners. Some stuff is just hard to find.
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Old Dec 13, 2014, 10:19 AM
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I am fairly sure it is M3 by .5 pitch. That is what mine is. It is fairly standard. If it is M3.5, the the pitch is .6 IIRC. That would also be the standard metric M3.5 pitch. The half sizes are much harder to find than the M2, M3, M4, ... It will likely need threaded rod with M3 x .5 if you are going 3". or use a tongue muffler or some other method. Three inches hanging out is going to be a weak point too with all the vibration.
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Old Dec 13, 2014, 11:12 AM
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My hobby shop has 3.5mm screws and the pitch isn't the same as what's in my engines. Took a pitch gauge to the screws. 3.5mm were .50 pitch at the hobby shop. Also .50 pitch is what McMaster sells in the 3.5mm screws. .60 pitch is not the standard pitch AFAIC.
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Old Dec 13, 2014, 11:26 AM
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Metric machine screws

I believe you'll find what you need here:

http://www.microfasteners.com/home.p...ction=0&page=2

Good luck,
Jim
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Old Dec 13, 2014, 11:26 AM
supreme being of leisure
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just looking now they do actually have M3.5 but only in slotted or phillips head. they also show slotted head M2.6 which is the hard to find ones used on a lot of smaller OS engines.
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