RE: Club FOX!
 

Here is some info from Duke Fox on how to adjust a Fox MK_X type of carb.

http://i248.photobucket.com/albums/g...re_article.jpg

RE: Club FOX!
 

I learned a lot from reading Duke's Mixture Column. That is how I learned to run a Fox Engine! At that time I had either been given an old Fox or found one at a swap meet. I had never seen any instructions. Good stuff for sure....

RE: Club FOX!
 

Fellas, I need help!!!

I maidened my new plane with a previously used Fox 74 Eagle 4. It is the older style crankcase with a new TN carb retrofitted. I have also replaced the piston ring (but not liner), and both bearings last year. I ran half a gallon of 5% nitro, 11% synthetic, 11% castor fuel through it last year on the bench, then switched to 15% nitro (with 5% castor) when installed on a previous airplane. The engine ran properly in the plane on the ground, but would stall at part throttle while flying.

After that, I had Fox Manufacturing replace the carb to the TN, and ran it on the bench with good results. Now, I have the engine installed on a plane and it runs well on the ground (2500 rpm idle, 10000 rpm WOT) with a 13x6 wood prop and 15% nitro fuel. Throttle response is great. Everything runs great on the ground. It is on the rich side. But when flying part throttle, the engine would quit. Sometimes when throttling up, the engine would stumble and quit while in the air. I had a glow plug with idle bar, and then replaced it with a medium heat range plug (Fox 8). But there was no difference. The engine does seem hot after deadstick landing since it is in a cowl (I have a lot of opening area for cooling, but maybe not enough?)

So, I am at a loss for what to do next. I could richen it even more, but I am already setting it fairly rich (10000 rpm max).

RE: Club FOX!
 

I think that maybe it is a touch too rich on the low speed needle. You might try leaning out the low speed a little more.

RE: Club FOX!
 

ok, thanks. I think I went the wrong direction with the LSN and richened it. Possibly making it worse.

RE: Club FOX!
 

Looks like Davis will have the Fox 15 in a couple of weeks, waiting on the next run , it will be shipped with the diesel head and glow button
He will post a pix



martin

RE: Club FOX!
 

Try a Miracle plug and lean the low spd needle a bit. Also, remember that the exit holes for cooling need to be a lot larger than the inlet holes.

BTW: why all that nitro?

CR

RE: Club FOX!
 

I have only 1 fuel and have been using it for all my engines, including 4-strokes. I have been considering going to 2 fuels, 5% with castor for my Fox, Irvine, and Super Tigre engines, and then 15% nitro for the other engines, including the 4-strokes.

RE: Club FOX!
 

if I remember right, the earlier Fox .74's had higher than normal compression and didn't like much nitro, if any, in them.
The newer engines have a different combustion chamber shape to lower the compression ratio more so the engine behaves better with more nitro in the fuel.

RE: Club FOX!
 

O/K, I have one for you motor heads. Finally fired up the Eagle IV 60 yesterday when I dragged the F-15 airframe to the field. This rig has the tank at the CofG with a Perry VP-20 pump and from the dimensions what seems a Perry 4300 carb, (throat I.D. nearly identical to the stock carb). Went through the procedures sent with both the pump and carb and got the motor to idle smoothly. The following problem occurs when full throttle:

The motor seems to peak out fine when adjusting the HS needle, then falls off a bit with no amount of adjustment getting it back again. I opened up the pump output several times in ¼ turn increments and the problem remains. Even if I get the motor running the best with any adjustment as soon as I lift the nose the motor will quickly stagger and die.

The entire purpose of this setup was to negate a known nose-heavy condition with this model and moving the tank aft was really the only option. As I have future model builds that require possibly even more radical setups, (Seawind, etc.) I was wondering if this is simply a case of a carb mismatch or what would normally occur if a pump was used to feed a non-pump carb.

I swapped out to another Perry carb, but have not fired it up again. Another option is to try the stock Fox carb. The fun there is the motor has to be shoehorned into the nose and with the carb base arrangement I cannot get to the screws with it installed.

The fuel is 10% nitro, 20% lube.

RE: Club FOX!
 

How new is the engine? How much fuel or time on the engine did you put in on it before you tried peaking it out for max power. it sounds like it was heat sagging and still overheating some. It may not be broken in yet. I have had a few Fox engines take a long time to break in too. It required a lot of patience as I had to fly the engine around rich. Then after a few flights it was too rich and I had to land and lean it out a bit and repeat, each cycle leaning out a little bit more, etc. Eventually it was a happy engine reving up and running like it was supposed to. But it took time though.

RE: Club FOX!
 

Sorry if I did not specify. This is the new engine I referred to a bit earlier where I adapted the longer muffler and hand drilled the pressure fitting into. From the best of my knowledge the motor had not been run out of the box yet.

I only ground ran it with the Graupner 11/7 3 blade prop, letting it idle through at least a half tank before throttling to full and back again momentarily to check LS mixture and clear it out. This was repeated for a couple of tankfulls. It was on the third tank I tried to at least hold peak and it would do that for a second or two, then sag where no amount of adjustment would compensate. There were no signs of overheating(I just took the two pics posted here) and overall the motor remained rich. It was trying to reach that momentary peak, then richen it up again that was unsuccessful.

Perhaps I need to break it in more, but I have never had this on any of my other 2-strokes and to be honest have not run a pump since an OS 40FSR/ tuned pipe rig back in the 80's.

I know I broke my own rule here with only one mod at a time to try and set things up before proceeding, In this application that would have been difficult, if not impossible.

RE: Club FOX!
 

may be just a pump issue. unhook the pump and bypass it. make hook up from tank to carb. with muffler pressure hooked up too. re-run engine and check for proper operation. i couldn't tell from the photo what perry carb. it is. is it a standard or ''special'' pump carb.? if it is a pump carb. it should have an extra little screw head on the carb. next or near to the fuel inlet. the vibrating pump should be used with a standard type perry or any carb. for that matter as it just delivers fuel via a little piston pushing fuel to the carb. the perry ''pressure'' pump uses case pulse pressure to pressure charge the pump carb. to insure enough fuel for the ''mid'' range enrichment because the pump carb. can experience lean out in mid range through throttle up to full power because of the large venturie bore. that is how the perry pump/card. can deliver an extra 1000 rpm.

RE: Club FOX!
 

Cougar_439,
Well the engine needs a lot more run in time. Not at idle but at full throttle where you vary the main needle to control the richness of the air fuel mixture. You run it rich and lean it out a little and back to rich. After a tank, you let it cool off to heat cycle it and repeat. As you continue to do that, it will get to where it holds the lean setting more and more. But after you get it to run fairly well, albeit rich, you can fly it like that, if the plane will let you fly at a reduced power level. otherwise you keep running full throttle and rich on the ground or test bench leaning it out and back to rich alternately. Eventually it gets to where it holds the lean setting better and better. Prolonged idling doesn't help the break in any. But the reason I tend to fly them rich is that sometimes the engine takes a gallon or more of fuel to break in, especially if it is really tight to start with as the engines are designed to last a very long time. Years ago I used to use a extra large fuel tank and let the engine run WOT and extra rich and I would go back inside and watch TV or something while it was running. Then after hearing the engine wuit running, I would let it cool off, then go outside to refill the fuel tank and repeat the process. The engine would get to where it held WOT at a leaner setting with the needle better and better. It just takes patience.

The VP20 pump isn't all that good for long fuel draws, the VP 30 regulated pump is a better pump for that. The VP 20 is a oscillating pump intended for 4 stroke engines more than 2 stroke engines. The 2 stroke doesn't vibrate like a 4 stroke does. it is more of a boost or assist pump. The VP 30 uses crankcase pressure and thus has a stronger pumping action to handle the longer fuel lines if the fuel tank is COG mounted. The gasoline engines with Walbro pumper carbs, use crankcase pressure to activate the pump inside too.

RE: Club FOX!
 

Fujiman, I noted the carb number best matching the measurements in the first post regarding this. It is NOT a pump type carb.

As for the -30, I had one spare and this type was what I ran with the previously stated OS rig. To install it there would have been no access as the only location would have been aft of the firewall. I do have room near the tank. However, I doubt I would get reliable pulse transfer to the housing.

I have contacted Gary Conley and he is planning to give me a call. Hopefully we can figure this out.

I will be a bit disappointed if the -20 can't draw fuel over any distance as that installation was what planned for the Seawind. The Saito 100 would have been fed from a tank down at the CofG between the wings. Not only is the line length to the tank approx 1.5 feet, but on that one there is a matter of lift distance as well. There is a method to attach the -30 to the case vent on a 4-stroke. Just never tried it before.

Earlwb, I'll try and put more time on the motor bypassing the pump and see how it goes. I'll also try and get a tach reading.

RE: Club FOX!
 

ON a completely different topic...

Ijust finished building an old-school Craft-Air Scout 15 and put a new Fox .15BBRC on it. It runs great, still running it a little rich to continue to break it in, but it hauls this plane around the sky just fine on 1/2 throttle with an 8x4 prop. I challenged the guys at the field (who mostly have no idea what a Fox engine is) to identify the engine. None could.

But they were impressed with how easily it started (first flip every time) and the power it made. They wouldn't believe me that it was just a .15.

Wait until I bring out my new Ultra Sport 40 with the Fox .40 on it. http://www.rcuniverse.com/forum/js/f...wink_smile.gif

Mark

RE: Club FOX!
 

I know that this may be a bit off topic. Just some added info for inveterate modders like me.

Gary Conley gave me a call this morning and after looking at the pics found what he thinks are several problems.

First is that a -20 will not work mounted vertically as it is here. Can't remember anything in the instructions regarding that restriction. He also confirmed earlwb in that this is not recommended for 2-strokes due to the short duration power pulses. From what he states it will be fine lifting fuel 12" vertically in the Seawind with the Saito 100.

Also, even though the stock carb is only marginally smaller at 0.330 throat diameter, he states the 4300 with the 0.340 throat, (shown listed for the S/T 46G) is too large for the Eagle IV 60. Along with that a pump app with a non-pump carb will never work to optimum, if at all. I'll have to take his word for it as the 9300 pumped carb he recommends has a 0.375 dia. Perhaps due to the pump feed a smaller bore is not required to get enough fuel draw.

Just a bit of info, the recommended standard 1300 carb has a bore of only 0.270".

His read on this is the motor would draw fuel on muffler pressure and venturi action alone at idle, but with the aforementioned pump orientation never be able to feed enough at high speed, especially if the nose is raised.

The end result is a combi of the -30 pump and 9300 carb, both of which he will bring to the Toledo Show for me. It will require hacking into the fuse aft of the firewall to gain access to an area to mount and tune the pump. In the meantime I will add the pulse fitting to the rear cover and work on the fuse until the bits are here before starting the engine again. The last thing I want is to run the motor lean during breakin.

On the subject of the pressure fitting in the rear cover, there is already a tapped hole started and I wondered if anyone could indicate the thread specs.

RE: Club FOX!
 

try screwing in a 4-40 or a 6-32 bolt to check thread size. but someone on this thread mite already know the size. fox only uses american hardware. hope this helps!!!!!!:)

RE: Club FOX!
 

I got one better than that. I have a Birdie 10 (Globals down sized old school Bridi Dirty Birdie) with a Fox 15 BBRC and converted to tail dragger. That little SOB is quick and aerodynamically clean. It flies straight as a laser like old school pattern. Other guys thought I had a 25 packed in the nose and were surprised it was only a 15. Here's the best part. One guy (I swear) walked up and thought it was electric until he got close enough to see it wasn't He was impressed with how quite it was and how well it idled. Very reliable little engine. I'm thinking about getting another for something else because I have an old torn up OS 40 I can use for trade in. But, maybe I'll use it to get an Eagle 60. That old engine is like a dollar burning a hole in my pocket. I feel like using it to do a little Fox shopping. :D

RE: Club FOX!
 

I haven't take a pic of the backplate of a newer Fox Eagle IV engine, but I think it looks like there is a raised tab on it for something like a pressure fitting.
In this pic below, I took while bench running a Eagle IV, you can see the raised tab like part inside the backplate. I don't remember seeing a raised portion on the backplate on older .60 Eagle III or IV engines.

I normally just drill and tap a hole for a 4/40 size pressure fitting. That way if something goes wrong, you can re-drill and tap for 6/32 instead. I try the fitting out and if it protrudes inside I file it off a little shorter to fit without going inside the crankcase. Sometimes a washer and lockwasher works too. I put a little non-permanent thread locker on it too and let it sit overnight.

Well while you are waiting you can always run a few tanks through the engine on a test stand.
:D

http://i248.photobucket.com/albums/g...Muffler_01.jpg


Oh yeah there is a raised part on the backplate of the newer Fox Eagle IV engines. I accidentally caught a pic of it here.So I doubt you will need to worry about whether itr protrudes into the crankcase or not.
http://i248.photobucket.com/albums/g...e_IV_60_07.jpg

RE: Club FOX!
 

My little Sport .15 plane has a Fox .15 on it too.
I can take off at 1/2 throttle no problem. It can fly like a 3d plane and hover and pull out of a hover with lots of power to spare.
I flew it maybe 20 or 30 times with the engine running extra rich and gradually leaned it out over time.

http://i248.photobucket.com/albums/g...port_15_01.jpg

http://i248.photobucket.com/albums/g...port_15_02.jpg

My .15 combat plane has a Fox .15 on it too. It is a old version of the Fox .15 engines from many years ago, but it still runs good.
http://i248.photobucket.com/albums/g.../HOR_15_01.jpg

http://i248.photobucket.com/albums/g.../HOR_15_03.jpg

RE: Club FOX!
 

Earlwb, what is that sport plane? Looks like a fun one.

And I'd love to get my hands on a Birdy 10 and build it w/ a Fox .15 on it!

Mark

RE: Club FOX!
 

I think it is more or less a copy of the Herr Mini_Sport RC plane. It was supposed to be electric powered. But I stuck on a glow engine of course.
Someone sells them on Ebay as a ARF Mini Sportster.
Like this one for example http://www.ebay.com/itm/New-Electric...item19cfa43fc8
It won't taxi at our grass flying field but with larger diameter wheels it willROG no problem.
It does great four point rolls and knife edges too.

RE: Club FOX!
 

The Fox .15 is a jewel! I have both the bushed and BB versions.

RE: Club FOX!
 

Cougar429,
   Another idea...
   I forgot about it but some guys actually mounted the VP30 fuel pump inside of the backplate. You drill a hole just big enough for a screw to screwed into the threaded hole after you remove the pressure fitting for the pump. the screw keeps the hole open when you glue it in place (lightly oil the screw to ensure the epoxy won't stick to it). You then glue the pump in with JB Weld or Machinist's epoxy. You can put down some epoxy and then insert the pump and screw it down with the screw. After the epoxy has cured you remove the screw and now you are in business. Oh yeah point the adjusting screw and the inlet and outlet lines like you want too.  Now with the newer Eagle IV engines that pressure fitting boss on the backplate is likely in the way, so you would have to remove it, if you go this route.