Needle valve extension - RC Groups
Thread Tools
Jun 22, 2009, 10:11 PM
Registered User

Needle valve extension

I have a simple stupid question about an extension for my needle valve so please don't laugh. I have a O.S 91 and it's going to be inside a cowl. In order for me to make adjustments, what can I use for an extension from the needle valve to outside the cowl and how do I attach it? Thanks everyone. You all can stop laughing now.
Sign up now
to remove ads between posts
Jun 22, 2009, 10:15 PM
Registered User
winning1's Avatar
The OS 91FX has a hole in the end of the needle valve. You stick a piece of piano wire or 2-56 control rod in there for an extension. There is a set screw to hold it in place
Jun 22, 2009, 10:36 PM
Registered User
The way winning describes is one way of making an extension. By the way all OS needle valves have a hole in them with a set screw for attaching an extension.
My method because I am lazy is go thru my box of stripped allen keys find one that fits the hole, trim the length to fit and attach - its done. The other advantage to the allen key is there is a flat surface for the set screw to seat on.
If the extension is going to be long and to take the strain off the needle from vibration you could solder a small piece of wire in to a short piece of brass tube and then solder a cap screw to the brass tube. Then drill a hole in the cowl and use a long allen wrench to adjust the needle.
PS Is this for your Texan?
Jun 22, 2009, 10:50 PM
Registered User
Ask 6 flyers and you will get 6 good suggestions. I use a piece of yellow nyrod/pushrod. In the end I use a short piece of 2-56 rod that I thread up in the rod. The other end of the 2-56 goes in the end of the HS needle. I sometimes have to thin down the short piece of 2-56 so it will fit the small hole in the end of the hs needle.The pushrod is flexible enough that it will bend and allow you to remove the cowl without removing the hs needle or extension. The part that sticks out of the cowl can be colored to match the cowl.

Jun 22, 2009, 11:07 PM
Registered User


Thank you everyone for your input. Hey Byron F long time no talk. Yes you're right this is for the Texan. I had to stop building for several months because my mother became very ill and I had to look after her. I'm happy to say that she is doing fine now and I'm back building again. Once again thanks everyone.
Jun 24, 2009, 12:25 AM
Registered User
I'll use a bit of wire most of the time. On a 120 size Gee Bee with an OS 120 FS I took a piece of throttle cable and drilled out an aluminum fuel dot to thread the cable through and soldered the cable to the fuel dot to make a knob. Routed this from the bottom of the plane through one of the ply cowling mounts to a set screw in the needle valve. When I needed to adjust it, I just reached into the bottom of the cowl, pulled the cable out, adjusted the needle valve and then tucked the cable/knob back into the bottom of the cowl.
Other models I've used a very small allen head screw that the threaded end would fit inside the end of the needle valve, use the set screw in the needle valve to hold it tight, then slip a piece of fuel tubing, say about a half inch over the end of the needle valve. This will give you a "guide" to put a ball driver through a hole in the cowl and into the fuel tubing finally to the head of the screw.

Jun 24, 2009, 04:26 AM
If your needed extension length isn't that great, I have used a large T-pin as an extension.
Jun 24, 2009, 10:21 PM
Registered User Wannabe
rodneygt's Avatar
Here's a thread with the same discussion and good pics from when I had the same question.

The set up in the pic below is working good for me. The only difference is that I've added a rubber grommet from lowes to prevent the vibrations on the extension from eating away at the hole - it looks a little neater too.

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Needle valve extension on a SuperTigre? gabe6090 Engines 9 Aug 10, 2009 09:32 PM
Discussion Another needle valve extension question rodneygt Beginner Training Area (Fuel) 26 May 03, 2009 09:42 PM
Help Gas needle valve setting question Thumas Fuel Plane Talk 9 Sep 14, 2002 01:21 AM
WTB Needle Valve assy for O.S. FP-40 Craig Logan Cars - Cars and Parts (FS/W) 0 Mar 08, 2002 07:18 PM