Club FOX!
03-22-2014, 01:06 PM
#3401
Any muffler that fits a Fox .60 or Rossi .60 will fit the 1.20 Fox twin cylinder engine without modification. I'm making a custom exhaust for mine at some point. I suggest you do some homework on this engine before planning to put it in the air. It is not your average twin cylinder engine. It is also not a low rpm lugger. It needs to rev! I've been doing extensive homework about this engine and am making new custom head buttons and the exhaust system I mentioned. Many come setup to run on 25% nitro fuel (at 2+oz/min!!!) and have the boost ports blocked. If you want to learn what there is to learn about this oddity, I can get you a link to some good information about it.
Last edited by 1QwkSport2.5r; 03-22-2014 at 01:09 PM.
03-22-2014, 06:11 PM
#3404
Fox makes a tilt up and tilt down muffler that you can get direct from Fox Manufacturing too. Those will bolt right on too.
You can find them on Ebay from time to time as well. What is really neat is to find a tilt up and tilt down Fox Quiet Muffler, as those are really nice mufflers.
You can find them on Ebay from time to time as well. What is really neat is to find a tilt up and tilt down Fox Quiet Muffler, as those are really nice mufflers.
03-22-2014, 06:18 PM
#3405
Hi, and thanks for the info. I have a lathe, and made my own head buttons for my .60 and .74 Fox engines. It is really too bad that Duke had to get the no nitro idea in his head, because I have an old Fox .78 engine that I run on 15% nitro, and it is the nicest running glow engine I have ever had, and I have not modified it in any way.. Anyway, I will experiment with this .40 of my brother´s. He is a new flyer, and doesn´t need to be fighting a balky engine, so I might be stuck with putting an OS 46 he has on the plane for him to learn, while I sort out the Fox for later use. (Yeah, I know, it's blasphemy, but OS engines really do work great right out of the box.) I love Fox engines, but have to admit the OS engines are good ones, and less fuss.
AV8TOR
AV8TOR
av8tor1977, I posted a while ago regarding mods to the heads. Cannot remember if I did the same to the 40, but I redid both my 50's and with the Eagle IV 60's I fabbed some new buttons out of 7075 alloy and milled them to different chamber shapes to evaluate the best performance, (I have some 1/4-32 plug taps in my engine rebuild tools). I accomplished this by using an old, short thread glow plug threaded into the button, (to prevent extending into the chamber) and then the plug was clamped into a cordless drill. I ran the chamber side against two different end mills; one was a rounded Ball End to do most of the material removal and the other one was a radius edge flat end mill to do some "Tweaking" on one or two of the new buttons. The ball end really was all that was required as even sandpaper can be used to remove any sharp angle changes at the outer edge of where the ball end mill did the cutting. IT IS CRITICAL not to touch the outer edge where it fits into the sleeve.
This was required to prevent detonation at the 10-15% nitro fuel I run throughout the fleet of 2 and 4-strokes. Fox were the only ones that exhibited this issue, likely due to the fact they were originally designed for low or no nitro content fuel.
NOTE: When one of my 60's was returned from service with pair of new heads, (another for the second Eagle IV) they looked remarkably similar to the one I did on the left.
If you PM me with your EMail I can send you the text file with pics of what mods are done to the heads. The same rules should apply to all.
p.s. One additional mod that I, (and I believe so far only hsukaria has posted something similar) have accomplished makes a world of difference. The only complaint I ever had with Fox engines was their rather loud mufflers. By fabbing this adapter for my pair of 50BB's, of which one is shown here, (and something similar for the Eagle IV's) I was able to fit larger mufflers that did not affect performance, but brought the exhaust volume down in line with the rest of the fleet. The most time consuming effort in fabbing the adapters was profiling the ports to fit the engine outlet on one side and the muffler inlet on the other. Lots of marking and filing.
I understand that most may not have access to tooling as I do, but profiling the head button should be possible with file, sandpaper and patience, perhaps using the same glow plug-in-drill concept to provide rotation.
This was required to prevent detonation at the 10-15% nitro fuel I run throughout the fleet of 2 and 4-strokes. Fox were the only ones that exhibited this issue, likely due to the fact they were originally designed for low or no nitro content fuel.
NOTE: When one of my 60's was returned from service with pair of new heads, (another for the second Eagle IV) they looked remarkably similar to the one I did on the left.
If you PM me with your EMail I can send you the text file with pics of what mods are done to the heads. The same rules should apply to all.
p.s. One additional mod that I, (and I believe so far only hsukaria has posted something similar) have accomplished makes a world of difference. The only complaint I ever had with Fox engines was their rather loud mufflers. By fabbing this adapter for my pair of 50BB's, of which one is shown here, (and something similar for the Eagle IV's) I was able to fit larger mufflers that did not affect performance, but brought the exhaust volume down in line with the rest of the fleet. The most time consuming effort in fabbing the adapters was profiling the ports to fit the engine outlet on one side and the muffler inlet on the other. Lots of marking and filing.
I understand that most may not have access to tooling as I do, but profiling the head button should be possible with file, sandpaper and patience, perhaps using the same glow plug-in-drill concept to provide rotation.
03-22-2014, 07:03 PM
#3406
The Fox 1.20 twin cylinder engine is a completely different beast than any of the single cylinder engines. The Fox twin is typically set up with the conical 25% nitro heads which is not ideal for most people as you can burn a gallon of fuel in an hour of flight time (or less). Also, and more importantly, is the cylinder charging problem related to the cylinder orientation, the push/pull action of the crankpin and the shared crankcase volume.
The design leaves some to be desired. Ideally, at the very least, use Eagle IV head buttons and rotate the forward cylinder so the exhaust port is facing the opposite direction as the rear cylinder. This enables the (more efficient) use of "normal" 5-10% nitro fuels and prevents one cylinder dropping out due to one cylinder getting overcharged during throttle transitions.
The design leaves some to be desired. Ideally, at the very least, use Eagle IV head buttons and rotate the forward cylinder so the exhaust port is facing the opposite direction as the rear cylinder. This enables the (more efficient) use of "normal" 5-10% nitro fuels and prevents one cylinder dropping out due to one cylinder getting overcharged during throttle transitions.
03-23-2014, 05:47 AM
#3408
Earl is correct - Duke Fox states in the instructions to let it rev up. Top rpm is 14,000 and should be heeded as the rear rotor and bearing is a tad smaller than the front (17mm front compared to 15mm rear I believe). It is said to be quite a smooth engine due to both cylinders firing simultaneously but consequently doesn't make the engine sound like a twin but more like a big single.
For those not wanting to rotate the cylinder, you will almost need to use an on-board glow system. The boost port on the forward cylinder should be blocked by the cylinder base gasket at the very least. My engine came to me NIB with both boost ports blocked but I won't use on-board glow so I'm going to run my engine with a cylinder rotated.
For those not wanting to rotate the cylinder, you will almost need to use an on-board glow system. The boost port on the forward cylinder should be blocked by the cylinder base gasket at the very least. My engine came to me NIB with both boost ports blocked but I won't use on-board glow so I'm going to run my engine with a cylinder rotated.
03-25-2014, 08:18 AM
#3409
Hi, and thanks for the info. I have a lathe, and made my own head buttons for my .60 and .74 Fox engines. It is really too bad that Duke had to get the no nitro idea in his head, because I have an old Fox .78 engine that I run on 15% nitro, and it is the nicest running glow engine I have ever had, and I have not modified it in any way.. Anyway, I will experiment with this .40 of my brother´s. He is a new flyer, and doesn´t need to be fighting a balky engine, so I might be stuck with putting an OS 46 he has on the plane for him to learn, while I sort out the Fox for later use. (Yeah, I know, it's blasphemy, but OS engines really do work great right out of the box.) I love Fox engines, but have to admit the OS engines are good ones, and less fuss.
AV8TOR
AV8TOR
You might want to find out from Fox if there are head buttons or head shims for your 40?
Yeah, I admit the OS engines are easy to start and run out of the box. But you have to pay extra for the purchase and the higher nitro expense.
03-25-2014, 10:23 AM
#3410
Yes, I checked and Fox has head buttons for the .40, but I pulled my brother's apart and he already has the latest head button in it. So I need to check into other reasons why it runs so finicky. Just haven't had time yet to do so.
Some people have a knack for tuning engines, and some don't. My brother is one of those that just can't seem to figure out if an engine is rich, lean, whatever. He battles terribly with engine and tuning issues even though I have tried to teach him about engines throughout the years. He is just one of those that needs a pretty "idiot proof" engine like an OS. They do cost more, but they do work well right out of the box with little or no fussing. I love my Fox engines, but I have to admit the OS engines are very good ones too, especially for someone that can't or doesn't want to work at getting it to run well.
AV8TOR
Some people have a knack for tuning engines, and some don't. My brother is one of those that just can't seem to figure out if an engine is rich, lean, whatever. He battles terribly with engine and tuning issues even though I have tried to teach him about engines throughout the years. He is just one of those that needs a pretty "idiot proof" engine like an OS. They do cost more, but they do work well right out of the box with little or no fussing. I love my Fox engines, but I have to admit the OS engines are very good ones too, especially for someone that can't or doesn't want to work at getting it to run well.
AV8TOR
03-25-2014, 10:28 AM
#3411
Yes, I checked and Fox has head buttons for the .40, but I pulled my brother's apart and he already has the latest head button in it. So I need to check into other reasons why it runs so finicky. Just haven't had time yet to do so.
Some people have a knack for tuning engines, and some don't. My brother is one of those that just can't seem to figure out if an engine is rich, lean, whatever. He battles terribly with engine and tuning issues even though I have tried to teach him about engines throughout the years. He is just one of those that needs a pretty "idiot proof" engine like an OS. They do cost more, but they do work well right out of the box with little or no fussing. I love my Fox engines, but I have to admit the OS engines are very good ones too, especially for someone that can't or doesn't want to work at getting it to run well.
AV8TOR
Some people have a knack for tuning engines, and some don't. My brother is one of those that just can't seem to figure out if an engine is rich, lean, whatever. He battles terribly with engine and tuning issues even though I have tried to teach him about engines throughout the years. He is just one of those that needs a pretty "idiot proof" engine like an OS. They do cost more, but they do work well right out of the box with little or no fussing. I love my Fox engines, but I have to admit the OS engines are very good ones too, especially for someone that can't or doesn't want to work at getting it to run well.
AV8TOR
. So, I'll stick to internal combustion.
03-25-2014, 10:37 AM
#3412
Yeah, if you let the magic smoke out of electrical things.... well, it's not good and it's usually expensive.
The only thing more blasphemous than mentioning an OS engine in a Fox forum is mentioning "Electric"!! YUCCKK!!
Ok, I'll admit I have a couple of park flyers for flying after the real planes are done flying, but if you tell anybody I'll lie about it. And yeah, I hate to admit this as well, but my brother likes electrics. I've threatened to disown him, but he still tends towards electrics because he can't figure out engines.....
AV8TOR
The only thing more blasphemous than mentioning an OS engine in a Fox forum is mentioning "Electric"!! YUCCKK!!
Ok, I'll admit I have a couple of park flyers for flying after the real planes are done flying, but if you tell anybody I'll lie about it. And yeah, I hate to admit this as well, but my brother likes electrics. I've threatened to disown him, but he still tends towards electrics because he can't figure out engines.....
AV8TOR
Last edited by av8tor1977; 03-25-2014 at 10:40 AM.
03-25-2014, 12:57 PM
#3413
Yeah, if you let the magic smoke out of electrical things.... well, it's not good and it's usually expensive.
The only thing more blasphemous than mentioning an OS engine in a Fox forum is mentioning "Electric"!! YUCCKK!!
Ok, I'll admit I have a couple of park flyers for flying after the real planes are done flying, but if you tell anybody I'll lie about it. And yeah, I hate to admit this as well, but my brother likes electrics. I've threatened to disown him, but he still tends towards electrics because he can't figure out engines.....
AV8TOR
The only thing more blasphemous than mentioning an OS engine in a Fox forum is mentioning "Electric"!! YUCCKK!!
Ok, I'll admit I have a couple of park flyers for flying after the real planes are done flying, but if you tell anybody I'll lie about it. And yeah, I hate to admit this as well, but my brother likes electrics. I've threatened to disown him, but he still tends towards electrics because he can't figure out engines.....
AV8TOR
03-25-2014, 02:07 PM
#3414
Both of you can join me on my team. I got back into RC after a hiatus by grabbing an electric heli. At the time I had no nitro support gear left, so this seemed simplest. After the 6th heli decided to yank some of my planes and motors out of storage, (OS 40FSR and Fox 50). Both ran beautiful right out the gate and things sort of ballooned from there.
Anyway, there are uses for electrics that nitro can't match, (anyone killing mosquitos with the cloud snorting out the bottom of a nitro heli may agree electric is much cleaner). Same goes for ducted fans. Electrics have nitro beat down into the dirt in that regard.
However, at the end of the day, when comparing the cost of a single LiPo pack to nitro fuel, I can fly for a LOT longer burning fuel than electrons. Besides, something missing when doing a flyby and the only reminder is of my last visit to the dentist.
Anyway, there are uses for electrics that nitro can't match, (anyone killing mosquitos with the cloud snorting out the bottom of a nitro heli may agree electric is much cleaner). Same goes for ducted fans. Electrics have nitro beat down into the dirt in that regard.
However, at the end of the day, when comparing the cost of a single LiPo pack to nitro fuel, I can fly for a LOT longer burning fuel than electrons. Besides, something missing when doing a flyby and the only reminder is of my last visit to the dentist.
03-25-2014, 02:21 PM
#3415
Quote: "However, at the end of the day, when comparing the cost of a single LiPo pack to nitro fuel, I can fly for a LOT longer burning fuel than electrons". Unquote
Here's to that! To me there are SO many advantages to gas or glow over electric. Much more power available unless you want to spend big bucks, instant refueling and flying again, real airplanes make noise, and I have a Fox .78 that has faithfully been flying for over 30 years without even being rebuilt, while I have yet to get a LiPoly pack to last me more than a year. What a laugh that gives me that the electric guys actually purchase sound systems to make airplane "noises" come from their planes......
I'll gladly clean my plane at the end of the day for all the benefits of internal combustion!!!!
Oh boy, get out the popcorn, 'cause here we go....
AV8TOR
Here's to that! To me there are SO many advantages to gas or glow over electric. Much more power available unless you want to spend big bucks, instant refueling and flying again, real airplanes make noise, and I have a Fox .78 that has faithfully been flying for over 30 years without even being rebuilt, while I have yet to get a LiPoly pack to last me more than a year. What a laugh that gives me that the electric guys actually purchase sound systems to make airplane "noises" come from their planes......
I'll gladly clean my plane at the end of the day for all the benefits of internal combustion!!!!
Oh boy, get out the popcorn, 'cause here we go....
AV8TOR
03-25-2014, 06:11 PM
#3416
Some people have a knack for tuning engines, and some don't. My brother is one of those that just can't seem to figure out if an engine is rich, lean, whatever. He battles terribly with engine and tuning issues even though I have tried to teach him about engines throughout the years. He is just one of those that needs a pretty "idiot proof" engine like an OS. They do cost more, but they do work well right out of the box with little or no fussing.
AV8TOR
03-26-2014, 04:57 AM
#3417
Most guys in my club run OS engines. But some of them rely on the more experienced guys to tune their engines for them. Heck, I got a lot of help when I was starting out. But some guys just don't want to progress to learn to tune their own engines. One guy last year destroyed his new warbird because he wasn't able to tune his engine, and he was running an OS.
04-17-2014, 10:23 AM
#3418
I have a new Fox .45 with the new style carb on it. It's been a really sweet motor from the start but I'm having a little trouble with the transition. The top end is set fairly rich and it idles very well but when I give it the throttle, the engine dies for a few seconds, recovers then gets going again. I think what is happening is that the plug is getting drowned when I throw the fuel to it, then it has to sort itself out. I've put my finger close to the exhaust at idle and I get a tiny amount of fuel on it but it's not spitting. Makes me think I can't be far off but I'm concerned about leaning the low end more. The plug looks good (a Fox long reach, not a miracle). 5% nitro, 20% caster and an 11 x 6 prop. I know that when the low end is set leaner, the engine gets that weezy sound to it like it's burning nothing but air. I've also had other engines transition much better with a fatter low end. Been flying just about all Foxs for over 25 years. Never saw one do this.
Carl
Carl
04-17-2014, 11:00 AM
#3420
How hot is the Fox long reach plug? If it is too cold, you could be setting your low end too lean to keep the plug hot and the idle from dropping when you remove the glow starter. I had that happen to me last year when I was running a Fox #8, which is a cool plug, with 5% nitro. When I would remove the glow starter, the idle would drop, making me think that the idle mixture was too rich. So I leaned the idle mixture more. Even though my transition was not bad, I would get the engine to overheat during flight at part throttle and blow the glowplug seal (on a Fox Eagle 74). So, I went back to the Fox Miracle plug and re-tuned.
04-17-2014, 05:20 PM
#3422
I prefer to use the Fox Long or Long RC glow plugs for general purposes. These are a mid range glow plug equivalent to similar other brands of glow plugs. The Fox Miracle plug is a more hot heat range plug good four four stroke engines, but it does work well in two strokes too. The Fox Standard Gold plug might be a little better though for helping a engine to idle better though. Fox appears to also make a four stroke plug, but I haven't tried it. I do have some Fox 2.0v plugs left over for use with a single cell lead acid battery. But if you have a variable adjustable glow ignitor you can use it on the plugs too.
04-17-2014, 05:25 PM
#3423
I have a new Fox .45 with the new style carb on it. It's been a really sweet motor from the start but I'm having a little trouble with the transition. The top end is set fairly rich and it idles very well but when I give it the throttle, the engine dies for a few seconds, recovers then gets going again. I think what is happening is that the plug is getting drowned when I throw the fuel to it, then it has to sort itself out. I've put my finger close to the exhaust at idle and I get a tiny amount of fuel on it but it's not spitting. Makes me think I can't be far off but I'm concerned about leaning the low end more. The plug looks good (a Fox long reach, not a miracle). 5% nitro, 20% caster and an 11 x 6 prop. I know that when the low end is set leaner, the engine gets that weezy sound to it like it's burning nothing but air. I've also had other engines transition much better with a fatter low end. Been flying just about all Foxs for over 25 years. Never saw one do this.
Carl
Carl
Anyway, it won't hurt anything to tweak the low speed a little to see what happens. If it likes it try leaning it a little bit more until you get to where it is too lean and then you can back it out a little and it ought to be spot on then. I would agree with av8tor1977 with this.
Last edited by earlwb; 04-17-2014 at 05:27 PM. Reason: add more info
04-18-2014, 04:34 AM
#3425
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My .02 worth on Glo Plugs, the old reliable Fox long plug with idle bar can't be beat. I've taken O.S. Plugs out, they don't have an idle bar, and replaced them with Fox Idle bar plugs and they went through the whole range without a glitch.