OS .40fp spraybar

If you have the needle valve out of the plane and in front of you, I highly recommend removing the spring from the needle itself. Cut or grind the spring and make it as short as possible. The knob can work like a pendulum hanging out there in the air which will make your run all over the map and it can wear out the threads in the needle valve itself due to vibrations which can destroy the plating on the interior of the needle and or spraybar. The knob or the spring will come loose and it will do this for you typically and most inconveniently on the day your raising your hand for your official flight. The spring where it contacts the needle needs to be scarified and soldered. The aluminum however needs to be JB welded to the spring. Roughing up the spring and a thorough cleaning of lacquer thinner or acetone works. Place the JB weld and heat with a heat gun and let it run into the coils of the spring. I like to let it form a filet to the backside of the knob. I have some good information for you in regards to tank size, prop size, etc. All of what I suggest could be used as a guideline to know what to shoot for. The FP can be a difficult one in regards of engine run. While the engine might be working currently for you as a side winder, once you cowl it in and start dragging a much larger plane around the table quickly turn and things may not work so well. Let me know and I can assist you in the learning curve. Ken

Thanks, Ken. The .35 is what I've been using primarily on the old 38 oz. Skyray and It's so consistent I haven't had to touch the needle since the weather was cold. I've read on SH that the .40 isn't nearly the sweetheart the .35 is either. I flew it a few times one weekend and it seemed fine as a sidewinder, and was then shelved as it's plane was a hunk of junk. So far I've had some limited experience with inverted engines, and none of it was encouraging. So I'll probably be tapping you for advice when the time comes. Thanks.
Rusty