I think I may have a solution, or at least part of one. Maybe it came from a comment I saw on RCU at some point. The idea is to slip the end of a 1" segment of heavy duty fuel tubing over the end of the needle valve. I tried just twisting a long length of tubing but it twists too much. But when I shorten it to a 1" segment and then insert a brass tube in the other end so that there's only about a 1/4" gap in the tubing between the brass and the needle valve, turning the brass tube turns the needle valve fairly easily. And it turns it from almost any angle.

The idea still needs some refinement, but it's a start.

I'd try a flexible wire/cable if it can be done. Cant say not being able to see it "live"
Doc

Abu, Since most of my engines are rear carb gassers now, you generally have very limited access to the needle screws. What I am doing on most of my models, is running small tubes, very well supported, right up to the needle screws. I bought a long, thin screwdriver that fits in the tubes and is guided right onto the head. All of this needs to be done quite accurately. I use 2 tubes, one for the low end, and one for the high end. THis will all depend on your carb, but I am sure you can make something like this work. Even if this tube has to be run thru your former.

Doc, I'll experiment with the cable. Vertical, I've used the guide tube trick on several models, including the Snipe. It's the only way on a serious scale model. The problem is that the exhaust ring on the 770 blocks direct access to the end of the needle valve. The tube would have to be coming in at, at least, 20 degrees.

That is a shame. Sounds like a serious afterthought in the engineering.

?????? ......

Ahhh ....It's a REMOTE needle valve, you can put it anywhere!

Just use a bit of the ironmongery you have used to mount the cowl & place it out through the gap at the rear of the cowl.

John.

Ah. Hadn't thought of that. I was thinking in terms of mounting it on the fuselage wall or something like that.

Below are photos of three possible solutions: 1) A thin hex-head driver that can work at an angle, 2) the silicon tubing over the needle valve method, and 3) a wire cable to the needle valve (with a little turning knob made from a fishing weight). All three are workable. Idea #1 might require that I mount a tube to direct the driver to the right place. Idea #2 works only if there is a brass tube handling most of the torque. The shorter the piece of flexible silicon tubing the better. Idea #3 seems like a good, simple solution, but even with this length of cable it takes a lot of twisting to make the needle move so precise adjustment might be fiddly. Perhaps what's needed is something like a combination of #2 and #3, namely, a short length of cable, which would allow it to be turned at an angle, and then the cable crimped into a length of 2-3mm brass (or aluminum) tubing to reduce the twisting of the cable by itself.

Yep, the cable, crimped in a 3mm brass tube, makes for more positive control. There's only about 1/4 inch of cable showing.

Here's the needle valve with its finished, flexible extension. i also add a bracket to support it so it's not bouncing around while the engine is running. At this point the engine is all buttoned up with plumbing done, glow system attached, fuel injection tube in place, and re-painted aluminum cowl bolted in place.

Now, I can start finalizing the radio installation.

If the fuel tube doesn't work, just put a "T" on the fuel inlet line to the carb. Plug the line coming off of the T. When starting, unplug that line, open throttle to full, inject a bit of fuel into that line which now goes straight into the carb, and then the engine. Plug the line, reduce the throttle to idle and start.

Let's hope I don't have to do that (since I'm not keen on disassembling everything. But I'm glad to head another option, so thanks!

If you can get to the muffler pressure, Fill tank as normal, then move the fuel filler line to the muffler pressure, open throttle, hit a couple of licks of the pump, flip prop; it will put fuel in the carb for sure. Just dont pump so hard it pops the fuel line off the carb or tank.

Another good trick!

Surface prep is very important before priming.

Sorry, I'm painting my laundry room...one track mind.

You mean I can't just spray the hot pink directly on the cylinders? :eek:

Yeah, you wouldn't want it to peel.

Took me a bit to figure out TFF's idea, then had a "well, duh" moment; good idea. I will try it on my OS 26 FS, which I can't prime by the usual finger over the exhaust for some reason. It doesn't draw well enough. It's my only four stroke that I can't easily prime. I actually put the choke flap back on the venturi and made a wire extension so I could grab it, but it's awkward to pull the wire and flip the prop at the same time.