So how do you do this? Do you just have a needle valve extension hanging out the side of your scale beauty? Or do set the throttle and then forget about it? Or do you have some other clever trick for hiding the access.

As I mentioned on my Snipe thread, I've heard of people adjusting the needle valve via screw driver in a brass tube. If anyone has a photo of such a setup I'd love to see it.

How they adjust it probably depends on the type of scale events they enter. In FAI (international and world championship events), having the needle valve extension hanging out in the breeze will cost you static points since it doesn't appear on the full scale plane you are modeling. Other than that, I can't answer your question. If you use the tube as a guide for a screwdriver, I would assume that it is rigidly mounted in the airframe so that the screwdriver comes out very close to where it is needed.

Abufletcher--

Sorry I do not have a picture - but is very easy.

This is the way I do it:

1. Remove needle valve from carb
2. I then drill out and tap existing extension hole (Use drill press)
3. Use very short socket head screw (1/4" or grind sorter if you like) with Lock-tite.
4. drill hole in cowl the size of the ball driver shaft. (It is important to line up access hole to the center of needle valve.

There maybe other ways but this is easy and works for me.

Mark

Mark beat me to it. I've done this on non scale planes too. Works fine.

abu, i like using a small horn slipped over the mixture screw (in flight mixture control horn) run a push rod or throttle type flex cable into the cockpit if open cockpit or access hath. you can push in and out to tune mixture. you can usually use a existing control in the cockpit like mixture knob or cabin heat knob for the control.
have your engine tuned as well as you can and then use the control for fine tuning for weather changes. i once used the throttle control in a cub for the tuning. just open the door and move the throttle for mixture. jeff

A method I have seen on a Fokker DVII was a remote needle mounted next to the engine with it's axis along the model. The remote needle had a very long extension through a tube to the cockpit area so the engine could be tuned by twiddling one of the scale knobs in the cockpit. - John.

Great ideas here! The drilled and tapped needle valve sounds the simplest (though the idea of permanently altering an engine parts is unnerving). On the other hand, I love the idea of adjusting the throttle using a scale knob in the cockpit! [8D] How is the "arm" attached to the needle valve?

I'm not sure I understand how such a "remote needle" would work. I can picture the idea of a long L shaped extension that one moves up and down to "remotely" turn the needle valve -- a sort of long lever. Is this what you mean?

BTW, I'd also like to include hidden/remote access to the idle set screw (which on the Saito is located in the center of the throttle arm on the opposite side of the needle valve).

I solder a flexible boat drive shaft to the end and snake it to a convient inconspicuous location.
DJ

Since I use all four strokes nowadays most of my engines [os4st's]have a hole in the needle valve with a set screw for an extention. it is a litle small for 2-56 so I drill it out to take a 2-56 and put a short[1/4 - 3/8]2-56 socket head screw in it held in with the set screw. Then with the cowl in plsce with a 1/8th hole you can run a ball driver straight in and find the screw pretty easlily. Thus you only have a tiny [1/8] hole in the cowl.

Boy, what a bunch of manual Tweekers!
On any plane that isn't weight critical I use a specialist servo driven remote mixer needle assembly.
I've 'em for both OS and Moki engines and there are several available from after-market specialists, BMV for example.
You basically set 'em up manually and then do the final tweeking (loads and loads of available adjustment) via a dial on the tranny!
Where have you guys been? The jet boys have used these for years, they work GREAT!
I had one in a CG Extra (shows how long ago the was) and I never touched the needle in several years.
Im surprized that you scalies just haven't got light of this. How many competition flights where you intending scratching because your engine went lean/rich 2 mins after take off?
Turn the knob on your tranny, fix the problem and save the round.

Nope! A remote needle valve is just another needle valve in the fuel line in series with the original needle. Some of the OS engines use a remote needle valve mounted on the backplate away from the prop. OS just plugs off the hole on the carb where the needle would normally go. What you can do is simply open the original needle, say, 10 turns so there's lots of flow & tune the engine with the remote needle back down the line.

Don't buy the Fox remote needle, I tried 3 & gave up, none would work, just garbage. Tower has a few brands listed. - John.

Don, when did you last fiddle with the fuel mixture in your car? I don't mean to sound like Brian Winch (ask another Aussie!) but you really should be able to set and forget the needle, assuming you don't alter fuel/plug/altitude/temperature(significantly).

If you must, tap and fit a caphead(allen) bolt in the needle valve, and slip a bit of fuel tube over it (nothing heavy - vibration + leverage = bad for needle valves), with a hole in the cowl just big enough to squeeze a corresponding allen key through. The tubing will guide it into the bolt in the needle valve, and fiddle away.

Needle valves? Tuning? Surely you're not thinking of doing the "F" word with your Snipe soon?

Cheers,

Cam

Nope. I'm still stuck on the P word. Panel -- which may need to have a small hole in it.

I understand what you mean thought about not having to constantly adjust the needle valve. I have a Magnum 52 which is PERFECT in all ways and I haven't touched the needle valve in more than a year. Usually though I need to fiddle constantly for several weeks with a new engine.

Does any brand of remove needle work with any brand/size engine. I still don't quite get the plumbing though. Is it just putting two needle valves "in a line," that is, the fuel tank to the remote needle and then the remote needle to the engine mounted needle (set wide open)?

I take a 2-56 socket screw, carefully grind off the threads on the last 1/8-3/16" and stick it in the little hole on the knurled knob on the needle adjuster and tighten the set screw. If it's way down inside a cowl, I make a guide of brass tubing that the hex wrench just slides through, and mount it on a stand-off, lined up with the adjuster and the hole in the cowl, with just enough clearance that it doesn't touch either. All you have to do is stick the hex driver in the hole, the tube guides it straight to the adjuster, no fiddling around trying to find the thing. All that shows is a hole about 2.5 mm in the cowl.

Yes, exactly. I would not want to put the remote needle too far from the existing needle, just enough to mount it facing fore/aft & mount it in a convienient position. Yes any brand would do (except Fox! [:'(]) but don't use one designed for a .40 on a 45cc engine as the holes for the fuel flow would obviously be too small.

For what it's worth I have never used one, it just struck me as a neat idea designed by someone else..

What I usually do is like suggested before, solder a cap head (allen head) from a bolt to the end of the existing needle & adjust it with a long allen key.

Like camdyson said, you really should not have to tweak a needle too much anyway once the engine is tuned. If you do it's usually a sign of some other problem, usually crap in the needle valve. I don't want to get into that most stupid of all arguments (should I use a fuel filter or not, the answer should be obvious) but with a proper filter fitted just before the needle valve this should never happen. - John.

The M2 size bolt slips perfectly into the hole on the Saito needle valve. All that's needed is to file a flat spot and put some locktite on the set-screw. I've ordered some M2 x 6mm socket head screws from Micro-fasteners. An M3 bolt filed down also works nicely. I can't believe I haven't done this before!


And, yes, the idea of running a linkage rod to the cockpit is REALLY REALLY cool!

I just take the prop and cowl off twice a year, late spring and early fall, reset the main as needed and fly. For brand new motors this could be once a week until I am happy with the tune. KISS principal