uliner

My Feedback: (2)

I want to run some 061 CL Norvel's on bladder pressure. It will be the low prssure bladders 1/32 wall. I have been told the NVA is not fine enough.

What is the OD of the needle, and who makes one tht will fit? Is is smaller or larger than the old KK needles?

A remote needle would be OK too. I tend to crashj a lot and break them

Dave

BMatthews

I wouldn't go by what folks say unless they've actually run the engine you have on that same bladder.  Yes, it'll be a little fussier to set the valve but that doesn't mean it can't be done successfully.  Try it first with the bladders you make up and see how touchy it is.  Then if you need it deal with finding an option.

combatpigg

My Feedback: (3)

My experience is that the splines on the needle valve knob engage the "clicker" too coarsely. So, you need to toss the clicker and use fuel tubing placed over the needle to limit it's movement. At any rate, even with thin wall latex bladders the needle will be hard to set.

It's possible to install a KK NVA. I drill and tap a hunk of aluminum 1/4-32 and then file the piece down to fit into the oblong carb body, then JB Weld it in. I've done a couple this way.

Your fine tuning to make a bladder system work is choice of prop. The smaller you go with the prop the less fussy the engine gets. A 5x3 is usually a good all around choice.

Instead of bladders, a pressure tapped backplate plumbed back to the tank vent works very well with the stock needle and this is what I'd recommend if your plane can accomodate a hard tank. I'd rather solder up a custom tank out of tin than mess with bladderizing a Norvel. The payoff is less hassles at the field when it comes time to fly.

uliner

My Feedback: (2)

I have tried the stocker and it is too lean to to rich in less than 1/2 turn. Thought about pressure reducers, but the hole would be real tiny. My big ones (25's and 15's )are a lot less less senssitive.

I had a nice AP wasp wiith a venturi and a fine tread NVA from a MP jet that worked well untill it mid aired and broke the needle I can't get another one.

The goal is to build a few 1/2 combat planes for practice matches and gereral fooling around and not have a 200$ engine in it. I can use spider wire and get a lot of practice matches in. I have had good luck with the wasp with rubber ducky 5x3's, and some russian combat props. The rubber ducky works well enough and it never breaks.


I will try with the clicker off.

fit90

I like Mr. Pigg's idea about the pressurized tank.  I run a Norvel .061 AME on a Norvel pressure tapped back plate.  I have had the best luck using the norvel ame venturi and removing the spray bar assembly and installing one from kittingittogether.com.  You will have to drill out the spraybar hole and then JB weld the new NVA in place but it is relatively hassle free.   I just start cranking the engine with an electric starter with the needle lean and slowly richen the needle until the engine starts and runs.  Adjusting the needle is fairly easy compared to adjusting the stock needle on any kind of pressurized fuel system.   You can also use the big mig venturi.  I have "re-bored" them and then installed the fine thread NVA as described above.  I have had good luck with these also.  It pretty much depends on where you want the needle valve to point.   AME venturis point straight out and big mig's are angled back.

Bob

combatpigg

My Feedback: (3)

I see what you're up to now. There really is no trouble free set up that I know of. 1/2As are better off crashing nose first on hard ground instead of sinking in soft dirt far enough to break off the needles. A clever mechanic will someday make a remote NVA that is plumbed into a sealed off intake.

fit90

Texas timers' website has some pictures of how their  fine thread NVA has been used in a remote NVA.  Great needle valves and website.

texastimers.com