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Question about old engines

Old 04-16-2010, 09:56 AM
  #1  
ShaneLittle
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Default Question about old engines

As some of you have read I recieved my old engines recently which need some TLC but my question is: I notice on the new engines the high-speed needle is situated aft of the engine these days, mine have it forward, right behind the prop. Is there a mod for old engines to move the HSN aft of the engine? Thank you guys!

Shane
Old 04-16-2010, 10:26 AM
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big max 1935
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Default RE: Question about old engines

OS makes one for some of their engines & FOX & K&B make remote needle valve assemblies. Sort of depends on just how old your engines are & what make. Good luck, Max H.
Old 04-16-2010, 10:46 AM
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ShaneLittle
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Default RE: Question about old engines

Sorry Big Max, I have an OS .46 and I believe a Tiger .45.
Old 04-16-2010, 11:25 AM
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MinnFlyer
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Default RE: Question about old engines

For what it's worth, a lot of engine manufacturer's are abandoning the "remote" needle valve as they tend to cause more problems than they solve.
Old 04-19-2010, 07:10 PM
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Star7
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Default RE: Question about old engines

To amplify MinnFlyer's comment: It can be tough in some models to route the fuel line to a rear mounted needle valve....the tank/firewall can be so close that you either get a kink or need a BIG loop that can produce vapor lock and whatnot. I've concluded the rear nv is a brilliant answer to a question I never asked. It can work well in fully cowled installations where you can pull the bracket off (eg. magnum engines) and mount the nv off to the side.
Old 04-19-2010, 09:09 PM
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Default RE: Question about old engines

Wow...I was just bellyaching about this last week at the field. I bought an OS 46 for my 10 year olds trainer and the remote needle puzzled me really. There is nothing good about them and I see the design has changed again so the needle valve slants away from the prop. For those that have trouble keeping their fingers out of the way Isuppose these formations help.

I can tell you though that my experience with the remote needle valve is not good at all. Its tough getting in there without a hemostat, I seem to get bubbles no matter what I do and it starts very, very hard. In fact, it is the only engine I ever use an electric starter on...and Imean ever! I hate it.

I like the comment about answering a question not being asked. Amen to that!!

Tom
Old 04-20-2010, 07:38 AM
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MinnFlyer
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Default RE: Question about old engines

One good thing is that on SOME engines, the hole where the NV used to be is only plugged with a screw, so you can remove the needle assembly from the rear mount and screw it directly into the carb.
Old 04-20-2010, 10:46 AM
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Default RE: Question about old engines

Hi!
Have used a remotely placed high speed needle on pylon racers as well as scale planes and it has worked just as good on any of them.
I always use the "Uni-flow " tank system or the Tettra "Bubbleles tanks in my planes.

The only engines that hasn't coped with a remote needle is the two OS FS .26 four strokes in my DC-3.
I even tried them in another plane just to test the system with a remote needle, but it did not work either. Perhaps it has something to do with not using silencer pressure on those engines.
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Old 04-20-2010, 11:15 AM
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Gray Beard
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Default RE: Question about old engines

Old school trick. Back in my control line/free flight days none of the engines had the HSN mounted remotely, some of them were really very close to the prop. We either made our own remote needle as shown in my photos or you could go buy a new NV with the spring steel already added. Today the NV is drilled with a set screw for adding pieces of steel to lengthen the NV to reach out of a cowl or you can install some spring steel and bend it away from the prop to keep your fingers away from danger. I did that on an MDS engine that had the NV way too close to the prop. Nothing hard to do. There must be a lot of Russians out there with shaved down finget tips!!!
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Old 04-20-2010, 03:33 PM
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jaka
 
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Default RE: Question about old engines

Hi!
There is a problem with long needles! They vibrate so that the needle seat gets worn out! Thats why needles should be as short as possible. I even cut off some of my high speed needles.
Old 04-20-2010, 08:21 PM
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Default RE: Question about old engines


ORIGINAL: jaka

Hi!
There is a problem with long needles! They vibrate so that the needle seat gets worn out! Thats why needles should be as short as possible. I even cut off some of my high speed needles.
That's very true, wears out the O-rings and/or threads. We would run the springs back at an angle and have them go through a rubber O-ring to keep them from vibrating. In a plane with a cowl I don't extend the NV, I drill and tap the top of the NV and install a hex head screw so I can adjust the NV with a long hex head wrench through a small hole in the cowl.Just another old school trick.
Old 04-20-2010, 10:57 PM
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Default RE: Question about old engines

I have always hated the big push for remote needles But thank heavens OS has saw the light and the newest of the OS Ax's such as my 25 and 35Ax's all now have Aft slanted main needles, not remote needles.

Also the popular ThunderTiger Pro series uses the nifty aft slanted needles, except for the earliest versions which used straight needles up front.

John
Old 04-21-2010, 07:17 AM
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Default RE: Question about old engines

Hey wait a minute....is that blood I see in the first photo? (grin)

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