hsukaria

I also had a good weekend flying my plane with the Fox 74 Eagle IV. I started out by changing the prop from 12x8 to 12x6. It ended up being quite rich with the 12x6 prop, so I re-tuned it to lean it a bit. However, it was still too rich at the top-end to give me enough power, but I couldn't lean it out more becauuse it would lean out when I pointed the plane up. So, out of pure (precision!) guess-work, I switched glow plugs from a Fox #8 to a Fox Miracle plug (running 0% nitro fuel). The plug change transformed the engine to a hot-rodder. Perfect performance for my use. I think that I could run 5% nitro with a Fox #8 plug, or 0% nitro with a Miracle plug.
Next thing to do is to try a diffferent muffler that is not so restrictive. I am running a muffler that is not the Fox, but similar performance based on earlier tests. I have a hacked up mousse can muffler that I have not tried yet. I will also look around for a tuned muffler, if I can get a good deal. I will do a muffler evaluation this winter when flying is not possible.

earlwb

Well with some Fox engines patience is a virtue as they can take quite a lot of time to get broken in. It is one reason I tend to rebuild a old Fox engine instead of just getting a new one. I have the old one broken in and loosened up good already.  But a new engine only gets better and better with each flight, it sometimes just seems the better part is taking seemingly forever to happen.

hsukaria

In retrospect, I would have saved money by buying a new Fox instead of a used one. I ended up having to buy a new ring, bearings, and carb for the old one that I bought used. And that meant that I still had to go through the long break-in period. But at least I learned how to do some engine work.

carddfann

Had a good time late yesterday just before dark with my 4-star 40 and Fox 45. Plenty of power and no problems. Soon Fall will end, weather turn cold, and I'll grab my big snoopy mug full of coffee or hot chocolate and let the balsa dust fly in my shop. Balsa dust in coffee adds character.

earlwb

Cougar429,

Years ago some others used Perry pumps or Robart pumps on the Fox .60 and .74 engines. Fox at the time suggested using the larger bore (.350") size MK-X carb along with a "A" low speed needle. The "A" needle had a leaner mid range taper to it, the standard low speed needle might have been called a "B" needle, I forget now. There was also a "C" low speed needle for a more rich mid-range too. Duke later quit making the A and C needles and provided instructions on changing the taper for the different purposes. You can rework the needle by chucking it up in a drill and using a stone laid against it. It is easy to get replacement needles, if you screw it up, which are much cheaper than going with an adapter for a Perry Pump carb or special OS 3 mixture control carb or Super Tigre carb. I'll look around for the instructions about making the needle change, I am sure its around here someplace.

It took me a while to remember, I figured this all out after I quit messing around with the fuel pumps on a Fox engine.

hsukaria

I can't believe you remember all these details. I can't remember where I put my shoes yesterday!!! That's good info though.

I imagine the needle won't have to be re-shaped if using a fuel pressure regulator instead of a pump?

earlwb

OK I found the old Fox carb instructions. Fox talks about tuning the needle as needed in these.

Here is the instructions from the Fox Eagle III:



and here is the early Fox Eagle IV with the MK-X carb instructions.

Cougar429

My Feedback: (3)

Thanks for the info. With what I feel are abysmal peak RPM numbers I seem to be reminding myself, (AGAIN!!!) why to avoid 3-blade props on 2-strokes. 4-strokes do not seem to suffer that narrow peak power band. I can also understand with 15% nitro the detonation problem would be more pronounced at those lower speed and loads.

I just bolted an 11/8 2-blade on the nose with an 11/7 standing by and will work the motor in some more once the weather cooperates. The Performance Muffler spec out that I need to get up into the 11-13,000 RPM range to get on the pipe. Fox shows 13K as max, so I will try and remain below that.

earlwb

The stock muffler tends to restrict the engine a lot. I did some tests and the Fox .60 engine ran just as good as my Rossi .61 engine ran using a Performance Specialties Ultrathrust muffler. I had made a bridge adapter for each engine to use the same muffler. But I was only running 5% nitro glow fuel through the engines. Both engines ran really good with the 11x7 prop I was using too. They sounded like .60 engines on a tuned pipe too. A wonderful loud howl out of the props and engines. Back in the day for pattern flying the prop to use was a 11x7 or 11x7 and 3/4 prop or a 11x8. Most all of the pattern guys ran 11x7 or 11x7 and 3/4 props.
I posted some youtube video clips of me running the engines like that way back in this thhread someplace.

hsukaria

It's hard for me to get used to hearing a 60 running an 11x7 prop. I came to the RC scene recently and the norm is to run much bigger props. I am running a 12x6 prop on my Fox 74, and a 13x4 on my Supertigre G51. Opposite extremes. There is a place for each I suppose.

Sport_Pilot

Flying styles have changed as well. Back when everybody tried to fly thier pattern planes as fast as possible, thus the higher RPM and short props with big pitch.

earlwb

Way back then the pattern planes all went faster and faster as the engines, planes and radio systems improved. Everyone was using retracts to streamline the plane even more. It was common to perform 300 foot tall loops, etc. Some guys had air brakes for performing loops and square loops and keeping the speed constant throughout the maneuver. Three consecutive rolls could be scary as you started right after the turn around way out there and you were way off out the other side for a turn around when you got done. The plane could be a speck almost gone in the distance.  Then the Tournament of Champions big money competitions came along and that drove the need for bigger planes that flew slower so the spectators could watch them too. Around that time the 4 stroke engines became popular when the FAI and AMA approved the 1.20 size engines for competition and everyone started going with larger airframes.  At first everyone used tricycle landing gear as you were judged for your takeoffs and landings too.  Then that all evolved into the 3D aerobatics we see today where the planes fly much more slowly and they do everything at a much slower speed. But unfortunately the competitions seem to have gone giant scale with huge airplanes now. Way too rich for my blood spending several thousand dollars on a plane or more.  But I guess it plays to the audience as they can see the huge planes easier.

 

Cougar429

My Feedback: (3)

I had some time to run up the F-15 and my new Super Skybolt this afternoon and with the 11/7 on the Eagle IV I had some more respectable numbers. It was a bit cantankerous at first, but still peaked at 13,400, (run normally rich it stayed in the higher to mid 12K range). I had to up the pump pressure a bit to reduce the leaning effects nose up. During the run it ate a couple of glow plugs again and as I temporarily forgot where my spare Fox plugs were hidden, (since found) after pulling the head to have a boo I installed an OS "F" for the final spin up. The engine is a lot more behaved now with a relatively stable idle and transitions without the gagging midrange. I'm sure as it breaks in and I get it tweaked it will be even better. If I have one complaint is that the Perry carb leaks fuel to blow back over the head. This has some nice smoke and stink on shut down and I'm sure will get a bit messy as time goes on.

I did not bolt on the 11/8 to check peak yet. As the lower pitch seems to get on the pipe pretty well.

hsukaria

I test ran my fox 74 with a mousse can muffler recently. It is a simple design, a header goes into the top of the mousse can, and the stinger is epoxied at the base of the can perpendicular to the bottom. So, the stinger points straight down. Using 0% nitro and a 12x6 XOAR plastic prop, I get around 10,600 rpms. That is the same output as with my MVVS Quiet Muffler. The only discernible difference is that the exhaust sounds deeper (lower pitch). Since then, I shortened the stinger from 1 inch long to roughly 1/2 inch. I will test again soon.

I was hoping to improve the performance, but to no avail!!! I now have a Jett tuned muffler, but it does not fit in this particular plane, too long. Maybe if I build the adapter a little longer, it would stick out the bottom of the plane more and wont bump against the fuse.

If the Jett muffler does not boost the performance some, I think that I will send the engine to Fox for evaluation this winter while the flying season is off. I just want to make sure there isn't anything else wrong that I am missing. Maybe this is the expected performance and I have to live with it. But just to make sure....

carlgrover

I'm glad there's still Fox fans out there. I've been flying them since the late 80's.

I had a wrecked .50 that I sent to Fox for a rebuild and they said it would be cheaper to buy a new one instead so I got a .45. HUGE difference in one of these new puppies compared to the old ones! Finish is vastly improved, new style carb, VERY high quality. I'm breaking it in on my Kougar right now; running it real rich and enjoying it. So far, it's been fantastic. Didn't have to do any of the old mods and "tricks" to get it to run right either.



Carl

fujiman

My Feedback: (133)

that's good news!!!!!! THANKS

carddfann

The 45 is my overall favorite and workhorse of my 40 size fleet. Very durable and dependable engine. We had a fun fly last weekend and I dragged out a plane with 45 attached that hadn't seen daylight in a year. The 45 started right up and ran great as if I had just ran it the day before. Yes, they're very much still going and have come out with some new engines lately like the new 60 CL, super stunt 35, 35 ceramic version, 50 gas, and other gas engines. My son even uses their blaster plugs in his nitro truck.
While most guys in our club use OS and Supertiger, I bring out my Foxes. Since then, some other guys have come out of the closet and brought their's out too. So don't let anyone tell you or pressure you what to fly. You fly what you want and makes you happy.

hsukaria

Our club has been shaming people into buying OS and using high nitro fuel. So, they are somewhat stumped when they see a Fox running on 0% nitro.

I use the Fox glow plugs on all my engines with good results.

roy3785

Hi all, This is my first post on hear but  have been looking for a while.I have a  40 and a 45bb and 50 i got the 45bb in 1976 with a fox tuned pipe  and this is the engine i would like to ask about. i talked to fox and after i told them what i have tried they suggested sending it to them but i am in the uk so do not want to do that. The problem i have is the engine cuts out maybe 1 in 10 times this happens within 5 seconds after take off if it gets past this it will normaly run the tank out. I have changed the carb, tried it with tuned pipe and with a silencer also with tk fuel pressure system. it has been in at least 5 planes and does the same. i have run 5 and 10% nitro running 10/6 and 10/7 props. any ideas thanks in advance.

Roy,

hsukaria

I was getting similar behavior from my fox 74 last year. It turned out I was having too much nitro, cowl needed baffling to divert more air to engine, run richer, smaller prop (but you already do that), and finally, a newer head button. I would try different glow plug temp ranges also. But mostly, for me it was going down to 0-5% nitro. Sorry I can't give a logical order of what to do first. Some of these guys who are experts can tell you what to do first. Probably start with the easiest, richer F/A mixture, then lower the nitro, then plug, etc...

carddfann

Hi Roy,

That might be a tuff one to get at. I never had that with any engine except for a Cox TD.051, which doesn't really help. Anytime the plane's nose tilted up or down just a little (even while holding it), the darn engine would quit. Needless to say it quit seconds after hand launching it as it climbed. I could never figure that out but I was a kid then and fairly new to the hobby. It would seem like something is making it lean out as the nose points up. Does it do it if you just hold the plane with the nose up then run ok holding it level? If so, have you tried setting the high speed needle a bit richer? Is your tank's pick up line at or as close as possible to being in line with the carb's fuel nipple? Its really important to have the right fuel tank locaton relative to the carb's nipple. Is the fuel line too long going from the tank to the carb? Too long a fuel line can cause problems because it can be pinched a bit due to air from the prop or G-forces in maneuvers. Could the fuel line in the tank be getting pinched as the plane's nose tilts up in a climb? Earlier in the year, I had a problem adjusting the carb on my other 45 and came to the conclusion my fuel was old. I had a new gallon of fuel with me so I tried it and the problem went away. Moisture in fuel can cause strange things to happen and its usually not thought of until after a person tries everything else. I knew it couldn't be much though because it ran perfectly before and I had just cleaned the carb so I knew it couldn't be dirt. By the way, I use 5% fuel with a castor/synthetic lube package and I add about a capful of extra degummed castor to it. There are good guys on here who know far more than I do so I'm sure someone can help. I'm curious to know what it turns out to be.

hsukaria

A fellow at the club was having engine trouble with the engne quitting a short tme after startnig it. It turned out that the high speed needle was rubbing against his fiberglass cowl and slowly leaning it out. Most likely that is not what you have since you've had this engine in 5 different planes. I would also check that all the engine bolts are torqued tight and not loose. Check that there are no leaks around the carb base (gasket) and around the HSN.

roy3785

Hi thankyou both for you replies, in 1976 when i got the engine it was put in a aerobatic model on its side with pipe when i got the problem i tried plugs all fox then fuel pressure system.i lost this plane due to engine cut. it has since been in others just to try it . with engine upright with pipe and no pipe fuel pressure and not.if you have it running on the ground you can put it at any angle you like.shake it no problem.when it flys if it gets over the first few seconds it will do any angle no problem.power on and off it has no problem.I changed the carb of same type no change.tank has been close as i could get it.same hight as needle high and low to needle. i put a fox 40 in 1 plane to see if that got the problem but it was fine.when it continues to run it goes very well.

carddfann

Yea, we have a jerk in our club too and another who mouths off about radios once in while. People like that try to bully or pressure others into using what they use as if you must submit and conform. Kind of reminds me of that cable or satellite commercial where the neighbors come over to the new resident and say "We all bundle" in a tranced voice when talking about bundling services and someone dares to break rank and be different. I've always marched to my own drum, said what needs to be said, and to hell with ya if you don't like it. I'll use what equipment I damn well please and the others can keep their pie hole shut or go to hell. I'm one of only a few that dare use Airtronics. How dare I use something besides Futaba? We'll, I've owned Airtronics or Sanwa and Futaba over the years and never had a bit of trouble with any of them. They are all good and I'm open minded about either brand. I happen to like my current Airtronics because I personally (just me) think they are childs play to program - very intuitive. As far as my Foxes go, I'm happy with them. They work for me and I have the satisfaction of buying something US made even though my contribution isn't going to make a difference whether Fox survives or not. Its just a few less bucks going overseas. That's my stump speech for tonight.

carddfann

The fact that it acts up in 5 different planes and you successfully used a Fox 40 in one of them makes this a challenging problem to me. It really makes it seem like its the engine. Seems like you have already tried these suggestions or checked them out. Few things are as frustrating as loosing a plane over something that's not your fault like interference, batteries, or other things. I hate to say it but to me this seems to be a case where a person needs to see the engine and go over it, but you're across the pond. I still have faith that one of the other guys on here can help who has more knowledge than I do. I used to have an old 45 from that time period. I'm not sure how old it was but it had the wart on the side. I got it in a blind trade through World Engines in the early 80's. I had it in a scat cat 500 (pylon or quickie type racer - I forget) and that beat up thing still ran great. It was my first Fox RC. Up to then, my Foxes were CL. I eventually sold it with all my stuff when I temporarily got out a while.