I'd go with the Hobby Fasteners ST NVA. You will have to drill ot the hole a little to get it to fit as it is a little larger in diameter than the Fox NVA. That is what I have done, and I see no loss in power due to the larger spraybar. Back in the day, I was asked a couple of times if I was running an ST 46. No, just a Fox 35.

Jim thanks for answering,.Here is another option would this assy work?

http://www3.towerhobbies.com/cgi-bin...?&I=LXMRB5&P=M

Another opinion:

If Fox intended for you to switch needles, they would sell the .35 without a needle...

I may well be the only person left on Earth that uses the stock Fox needle.

There once was another...George Aldrich swore by the standard Fox needle valve and his "pinch corner" tank.

Replacement needles are easier to operate but not absolutely necessary.

George

George,
In your earlier post, you stated, I could not get consistant runs with the Fox NVA and replaced it with a Super Tigre NVA.

I removed the Fox needle valve assy from every Fox engine and used a Super Tigre NVA. Some versions are a little bit bigger around than the Fox NVA and they can be filed down in the area of the venturi to restore the intake area. I always considered using the old, crude Fox NVA a waste of valuable practice time. I used Fox 35's on several models for many seasons and have virtually thousands of consistent flights with this set-up.
Chris...

My Fox 35's had the old style flat end Fox needle. I could not get a consistant run. Three flights in a row without touching the needle, and each was quite different. So I switched to an ST NVA. I meant to open up the venturi a little, but never got around to it, and decided it was not necessary. The Fox 35 I'm flying at the moment has a too long ST NVA, so it has a couple of the white plastic washers you get at Ace Hardware to make it fit. People will tell you other NVA's are better, and maybe so. However, I have run ST NVA's for over 30 years so I am used to their foibles.

Must have been another George, I mentioned decreasing bypass size to increase velocity to cure or lessen the "Fox burp". All my Foxes have original needles. Most folks don't want to fiddle with Fox needles so they swap them out.

If you are trying to get the best run out of your Fox, you might also check out the Hemi heads and Stuffer backplates. It all depends on how far you want to go with your Fox .35. I currently have only one .35 stunt...it has a hemi head, stuffer backplate and standard needle.

Some of the guys who are offering advice have much, much more time on the Fox .35 than I so I would suggest taking their advice. I was just offering alternatives.

Good luck with yours.

George

Sorry guy's got the posts mixed up.

The Hobby Fasteners item, by all means!

Both are of excellent quality, but I'd suspect the ST NVA is a bit larger in diameter. The Fox Stunt 35 doesn't make great thundering gobs of power with the stock (1/8" diameter) spraybar; why close the throttle to half with a spraybar of almost 1/32" larger diameter? Hobby Fasteners makes?made their NVA specifically for the engines listed.

And at that price? No question... (It's bound to creep up, ins't it?)

Lou, are you saying by installing the ST NVA is going to cut down on the power because it is larger?

You do lose a small amount of air with a larger diameter spray bar. I would not worry about this. I never had a problem with my Fox .35 running with the stock needle. But...here we go, I would not recommend a Fox .35 today anyway unless you are experienced and know how to handle engines. The new, modern engines are much easier to deal with and produce a ton more power. Just my MO.

I had every intention of drilling out my Fox 35 intakes after switching to the ST NVA but never got around to it. I had a hemi head on the engine I am flying now, but I took it off because the engine was overpowering the airplane and flying it too fast for me with an 11 x 5 Taipan prop on 62 ft lines. For some one who understands them (and has good ones) Fox stunt 35's are fine engines; powerful and reliable. However, I would not advise a new flier to buy a Fox stunt 35 for a first CL engine.

Ok, I have these old engines Fox 35,19,15 and a Macoy .35 redhead, and money is alittle tight, or i would have went with the newer engines of today.So this is why i'm asking so many questions, i should be able to get these engines to perform well enough for the flying i will be doing out at the ball field.

ALSO IS THE FOX MIRACLE PLUG WORTH USING?

WHAT IS THE HEMI HEAD, WHAT IS IT ABOUT THE HEMI HEAD, THAT IMPROVES THE PERFORMANCE.

Jim Thomerson
why did you make this statement. ( I would not advise a new flier to buy a Fox stunt 35 for a first CL engine. )

I don't like them, but many people do use them with success. I use a hot Thunderbolt from Hobby People.
Lou Crane's idea about the thinner NVA from Hobby Fastener's is a good one for the Fox 35.
Use 25% oil, castor only or castor mix 50/50 with synthetic oil for those old engines and they'll run well for a long time.
If you need a few more HP and can swing the bucks, 15% nitro in the Fox will help it move a pretty big model. The McCoy 35 is just a bit less powerful. Both can fly a 550 sq in Stunter OK. Use 10x5's and balance them well.
McCoy needle valves work pretty well for me, BTW. Never had to change them out with anything else.
People still use these engines in Classic Stunt and Old Time Stunt events with some guys doing quite a bit of practice flying, so they are still viable especially for the school yard.
Have fun,
Chris...

If a person doesn't have a balancer, is there something that you can make that will do the job?

I have purchased some sig champion 10% nitro. And will add some more castor.

I tried a Fox miracle pug in a K&B 4011 and did not like it. Other folks swear by them. As said, I mostly run the Fox 2 volt plugs. The Fox 35 hemi head was designed by Marvin Denny. Most modern engines have a hemihead of some type. I think it provides more efficent combustion, thus more power, than the stock Fox head.

With a modern ABC or ABN engine, you don't have to break it in like an iron and steel engine, and you can run some fuel you got at the hobby shop. I've flown a Tower 40 a lot and really like it. I'm building another airplane for it at the moment.

The other Fox engines and the McCoy 35 will give you a lot of good use. I flew a McCoy 35 a good bit and perhaps liked it a little better than the Fox. But the Fox is still in production and one can get parts if needs be. I have several of the McCoy 19's and they have served me well.

Hi JaySeas,
You can put a shaft or dowel through the prop hole and prop it up on two razor blades held vertically on the bench by wood, glued to the bench, etc. This way a heavy blade can be readily seen as it drops with gravity. I sand the front of the heavy blades to balance.

Sig fuel is very good and consistent. I use it often. Adding castor to it will make for a good mix for these old bushed engines.
Chris...

Thanks Chris for your help.

I want to say thanks alot guy's,for the info you provided, today i put it on the test stand, using sig 10%nitro fuel, a enya nva, a sig R/C 003 glow plug and with pressure with snow starting to fall she fired right up on three flips, and she is running good in all positions, it has never sounded so good.Now to mount it back into a plane.Will let you know how it works out.
thanks again.
Jim

Hey that's great, Jim. Keep us informed of your progress.
Chris...

Jayseas,

Sorry for the long delay in answering about a larger diameter spraybar costing power from a Fox 35 ... (Got diverted to other things that took mucho time.)

It's mostly theoretical, since reduction in effective throat area will affect power at the top end, but not much where we generally set a Fox 35. Fox 35s, run as we usually do, can last a long time. Run them much above 13,000 RPM and they don't last too well. So, we stay around 10,000 RPM max, with plenty castor...

The original Fox 35 needle, or at least the early one Fox made, has peculiar handling. (I think the very first Foxes used a Perfect or Kap-Pak Universal, or something like it, back in the early 1950's... Both of those companies are long gone. ) Over the years, Fox production precision has, shall we say, varied. It's been MUCH better the past 10 or 15 years... What complicated the 'standard' flat-one-side Fox NVA was often too loose a fit between the threads on the needle and in the spraybar body.

That allowed motion inside the spraybar, around the jet holes, which may have changed the setting intermittently, and made fine tuning a setting iffy. A simple partial cure for that was/is to cut a snip of fuel tubing that will still be compressed at running settings. Slip it on the needle, between the inner knob and the spraybar. This does two things: the compressed fuel tube 'loads' the threads into a snugger fit, and the tubing acts as a seal against air leaks.

The flat tapered needles also seemed to vary the setting as you sneaked up on what you needed - almost as if it went richer when the flat faced one of the jet holes, then leaner, within 1/8 to 1/4 turn, as it more like blocked both, then richer again as you turned it leaner. Once you got closer to a final good setting, the stair-stepping didn't seem to matter as much. It was getting there that took too much trouble.

I like the OS or ENYA NVAs. They are close to the stock 1/8" OD spraybar diameter, and are beautifully progressive.

Hey thanks Lou, for getting back, things come up that is for sure, and if you saw my earlier post you see i went with a enya nva, that i'm also using a peice of fuel tubing. the fox .35 seems to be running fine on the bench, i mounted it to a short peice of 6" x 6" so i could moved it around the differnt axis to see how it reacted to the different positions and it is doing that 4 2 cycle run. Now i need to see how it performs in the plane.
thanks again.
Jim