Fox .25 NVA's

[Ed Carlaw]

Hello to all, I am returning to the hobby after a 30 year hiatus from flying. During the dig out of old equipment, my Fox .25 suffered a broken NV assembly. I would like to know if these are still available or if there is an alternative setup that would better suit the engine and my relearning the flying end to this great hobby. Thanks, Ed.

[Bill Little]

HI Ed,

There is a good possibility that Fox still has them.  They can find a lot of older parts down in the warehouse.

Marvin Denny (Bigiron) would be a great possibility, also.

Big Bear

[Ed Carlaw]

Hi Bill, thanks for the reply, I'll try Fox. Was just curious if the .25's have the same quirks as the .35 pertaining to NV settings. Was reading a couple of the posts on the .35 about the course threads on the needle valve and sometimes how a good setting is tough to achieve, not that I'm going to be competing or anything, but I would like my introduction back into the hobby to be as smooth as possible. I don't recall having any issues before, but like I said I won't be competing just yet, but getting my "sea legs" back. Thanks once again, Ed.

[M Spencer]

You can do couston needles as its little more than a treaded wire .
Stock ones vary a bit , and the spray bar  dia really needs the fuel line wired on.

Noticed one of my intakes has the spray bar back away / off centre .

So puttem ' under the microscope ' and fit a neddle protector if side mtd , if it sticks up.

[Bill Little]

Hi Bill, thanks for the reply, I'll try Fox. Was just curious if the .25's have the same quirks as the .35 pertaining to NV settings. Was reading a couple of the posts on the .35 about the course threads on the needle valve and sometimes how a good setting is tough to achieve, not that I'm going to be competing or anything, but I would like my introduction back into the hobby to be as smooth as possible. I don't recall having any issues before, but like I said I won't be competing just yet, but getting my "sea legs" back. Thanks once again, Ed.

HI Ed,

If this is the "modern" Fox .25 (4 bolt back plate and bolt on venturi/carb) it will not run like the old Fox .35 Stunt in "stock form".  it is a solid 2 cycle run type of engine, not a 4-2 and will run you crazy trying to get it to run that way.  Use a 1-4 APC or similar and set it just shy of a peaked 2 cycle.

I "LOVE" the old ('54-'57) 3 bolt back plate Fox .25 which was built in the .19 case.  Thinks it's a Fox .35 Stunt!  About the same power, and just a but less fuel needed.

Big Bear

[Ed Carlaw]

Hi Bill, it's the 4 bolt backplate with the bolt on venturi, so I guess I won't have to fiddle too much with the settings knowing it's a straight 2 cycle. I guess this might be a little in the beginnning for me so I can get some practice time in and not fuss too much with the engine-that will come in time. Thanks again, Ed.

[Hoss Cain]

Hi Bill, thanks for the reply, I'll try Fox. Was just curious if the .25's have the same quirks as the .35 pertaining to NV settings. Was reading a couple of the posts on the .35 about the course threads on the needle valve and sometimes how a good setting is tough to achieve, not that I'm going to be competing or anything, but I would like my introduction back into the hobby to be as smooth as possible. I don't recall having any issues before, but like I said I won't be competing just yet, but getting my "sea legs" back. Thanks once again, Ed.

Back way before dirt when I ran a number of Fox engines, mostly Stunt .35s, but did the .19, the .29, and the Stunt .40. Most of my stunt competition was with the Fox Stunt .29 & .35, which was over a period of some 15 years. In addition I had a George Aldrich custom ST .40, fantastic, and a Johnson Stunt Surpreme .35 with a restrictor in the venturi. 
Over the few years that I competed regularly, I always used an O.S. needle valve with the single hole facing directly reaward just out of sight.  If I really get back into it, I'll be doing same. But at 75 years young it will take more than the right NV to make a difference.  

 Heck, I even won a couple contests flying a Thundebird ( much modified) with the JSS, and George Aldrich was the head judge. GA did not really like Palmer's models in his events, especially with a Johnson engine.      

[Ed Carlaw]

Hi Hoss, you said you used mainly the.29 and .35 with an OS needle valve setup. Did you use the OS setup in the .19 also? If so was just curious how the engine ran compared to stock Fox needle valve assembly and if any modifications were necessary. Thanks, Ed.

[M Spencer]

Some mug here has enough 19 / 25 s for a Spruce Goose ,3 are 25s .

5 - 20 % nito , set richer with the higher, will 4/2 . set about break .

the 19 & 25 tecnically turn 9 x 4 s at the same RPMs (on 5% nitro )
according to Chinns engine tests.

I usually use em in twins, with the Two .25s , 9x5 zinger's worked good
on a stunt type run .

The 19s are crankier. At one stage , same head clearance , id set em
both at 6 or 6 1/2 turns and theyed be fine .

Lately used doubled blue tube at spray bar, had used bit over , with
the tube over a 8 mm long piece , the blankety thing restriced ,
Blowing fuel tube to set needles same ( Same ' Hiss ' ) woke me up
to this as wernt a lot of hiss on one ! Mutter mutter mutter .

So I wired em on.

Fuel Line Tends to skew , & come loose and / or may leak , on Std. tube .
Where it goes on the spay bar . Traps for wary players .

Outside of that there nice rowdy rorty devices , the 19 being
more hooligan than the 25. ( big brother ! )

Spray bars are fairly small dia. Havnt measured em.And there not
long. Late ' waisted ' OS 15 ones may fit. But these are hopeless
in OS 35s and G-15 FIs, you wind em out running , past 5 turns it
makes no differance . The outlet HOLE aint bigenough for a greedy
engine. So one could drill it out ! but there must be a simpler way .

So I await with intrest for the hot tip on the spaybar !(MVVS ? )
Now I will have to go and measure em up.

A narrow blade 10 x whatever , like a master airscrew should be fine.
Ive some ancient 'Gorrie Mit ' ! 10 x 4s ive oiled , look like Teak ,will
use em before the end of time hopefully when a DeH 88 is fully sorted.

[Bill Little]

HI MAtthew,

I am interested in the 4 bolt back plate doing a good 4-2.  We along with several others, including Marvin Denny (a real Fox guru), could never get that engine to do anything but a wet 2 with them being "stock".  IIRC, Dean Pappas breathed on Bobby Hunt's 4 bolt back plate Fox .25 that he used in the Frisky Pete he published.  Maybe he will see this and chime in.

Strange......

Bill

[Hoss Cain]

Hi Hoss, you said you used mainly the.29 and .35 with an OS needle valve setup. Did you use the OS setup in the .19 also? If so was just curious how the engine ran compared to stock Fox needle valve assembly and if any modifications were necessary. Thanks, Ed.

I never flew the .19 in competition. In fact I did not do much with any engine below .29 except for just funsies so the set-up was not really any big thing. However once I learned from someone along the stunt trail about the O.S./Enya NVs I used them exclusively. If the throat was small, I just placed some washers in place outside the venturi to center the hole in the throat.
One thing about my stunting days, I always used exclusively Fox Superfuel, at 5% nitro and 29% castor. That stuff worked and worked well in all my engines including my .40 ST that was rebuilt by GA. Back in those days, only finger starting was allowed. Rules gave points for airborne within 1 minute from signal. That ST was flown for about 3 years, and it was,  Prime, turn prop over to get the bump, signal judges, flip ONCE and head for the handle.

However in the last couple years I also flew the Fox Stunt .40 for a while. I broke it in on a MW profile ME-109 for several hours and it was - with the OS NV - just as good as the ST. I have a new one in box and it will get its chance later this year.

[Bill Little]

Hi Hoss,

I actually spent almost one year after the "Starting time" rule was dropped with out knowing it was gone! LOL!!  I was timing everything to make sure I was started and flying before the "one minute" was up.  Now it doesn't matter....... just get the wheels stopped before 8 minutes expires after you signal to start.  MUCH easier (it takes longer for me to get to the handle than it used to! LOL!!).

The Fox .40 (big case-'70s) Stunt always has been a good runner for me.  I like it, too!  I was working part time in a hobby shop when they first came out (1972, IIRC, or thereabouts) so I was able to get one.

Bill

[Steve Helmick]

Randy Smith has an "Aero Products" NV Assy. to fit Fox .35 Stunts, bolt-in.  I'd guess that it'd fit the .19 and .25. But Randy would know for sure. They're not cheap, but are absolutely the best you can get, I promise. I would NOT bother with an OS or Fox NV Assy.    Steve

[David Miller]

I have a Fox .25 just like yours. I am not an engine guru. I run mine in a Flight Streak ARF with 10% fuel which I add a little castor too. I use a Master Airscrew thin 10 X 5 and it does the beginner stunt pattern just fine. I think it would be a good combination for you. Especially just starting out again. Good luck and let us know how it goes.

[Bill Little]

Hi David (and ED!)

I didn't want to scare anyone off from running one of those Fox .25s.  Like i mentioned before, my oldest son's first "full size" plane was a Flight Streak and one of those .25s.  We went through 3 crankcases (all broken in crashes!! LOL!!), but the plane still lives and is getting restored.

It's just if Ed flew Fox .35s before he "retired from flying" and when coming back expects the .25 to 4-2 he might get disappointed, that's all.  If run in a "wet 2", the engine finally did great for us!  I tried to run it like a Fox .35 at first, that's all I knew, but finally decided to stick a 4 pitch prop on it and lean it out to a 2 cycle.  It did fine from then on and was plenty strong enough to fly the 'Streak, running about a 5.0 lap on 60' eye to eye lines!   We just happen to have a few OS .20FP BBTU engines and one will go on it this time.  Just for kicks.

Big Bear