Now that I got your attention lets discuss (with real suggestions) how to make this motor run. I had the first Eagle .60 version I which ran well. When this engine finally wore out,, I sent it to Fox and they were gracious enough to replace it with an Eagle .74 + $$. Ok,, I need no comments here .. The Replacement Eagle (I will call engine #2 ) would never transition to full throttle from idle. It would turn ok at full throttle and Idle but not accelerate without dying. I replaced the carb with the new "easy to adjust" air bleed. The problem did not go away. Finally after much !@#$# I gave the engine away. Well guess what.. Yup you got it,,, I was given another Eagle .74,, (engine #3). So,, my thoughts are,, maybe the first was just a bumb engine. So I have been attempting to break in the "new" Eagle #3. But still same problem won't transition. I know Fox states 5% nitro and castor,, I even used Fox gold star fuel made exclusively for this engine. Same problem. Adding castor,, lets not go there,, didn't work either. I even made and extra head gasket to lower the compression,, no help. Engine #3 is running with the Perry carb and adapter. The engine runs smoother and idles well but still won't transition. Top end with an 11x8 MAS prop is 11,800 which is ok, and idle is really good, but didn't tach it. When the throttle is opened up at a ("Normal") rate for a go around from bad approach the engine blows fuel out of the carb and quits deader than a hammer. Every time it does this and is repeatable. I have tried fuel at 5, 10, 15% with 20% castor, 10% castor 0% castor and 20 % syn. then 18% syn. The plugs were Fox idle bar,, OS F and Hanger 9.

My suspensions are the timing of the ports on the crankshaft open too soon trying to get air quicker but allows compression gasses to blow out of the carb interrupting the flow of fuel,, then dies immediately. I really think retiming the crank (which I won't do) or possibly a fuel pressure regulator to control pressure on acceleration.

I know this engine will attract many of "those" comments for fun.. but please keep this professional. Currently I do not plan to fly this engine when Enya, OS and Saito are around. But it would be nice to say "WE" solved this problem.

I have spoken to FOX reps many times on this problem but they have not provided any useful info on this engine. I think this is a design problem.

So thank you in advance if you can provide some light on making this engine transition from idle to full throttle. Vettdvr

You want to go to www.flitelinesolutions.com The information there in good and very helpful. Some of the Fox reps' can't really help unless they are there with you and your engine.
But it still sounds like you have the idle to rich. At least that's what it sounds like to me. What is the enigine mounted in? Upright, side or inverted installation?
An 11x8 will work, but will work better with a tuned pipe, the .74s' that I've used where happier with a 12x6 or 13x6 with the stock exhaust.

I have tried the 11x8 and 12x6 with stock exhaust. I have also adjusted the idle (airbleed) from full open to full closed, with no improvement. Perhaps the pipe is the solution. However I am using it straight out of the box with the Fox tilt down muffler as designed. Thanks for the input.. vettdvr

You stated that you had run the engine with a Perry Carb. And still had the problem! I tried a Perry on one of mine and it cured a lot of transition problems and a lean mid-range. You should take a serious look at the Fliteline Soliutions web site.

Doug I did look at FL solutions. What I find interesting is the modifications to the button to lower compression. I plan to make the mods today to mine. (I have a lathe and can do the work). I used the Perry on both of the .74's with little change. Granted they did improve idle and top end was ok,, but the transition kills the engine everytime. If it idles for 20 seconds or more and the throttle is advanced with a servo, it will blow back through the carb and instantly quit. Not a very nice thing when making a go-around to have the engine quit. I flew the first .74 in my P51 and after 39 deadstick landings finally missed one and lost the plane. But I am now retired and willing to diddle with the remaining .74 to see what will "fix" this problem. The engine is very solidly built, but I find it hard to believe that any ran right out of the box after breakin. Nitro from 5 to 15% all resulted in the same poor transition problem. The 15% does generate more heat but transition is where it dies. This is why I think the crankshaft port is cut too agressivly allowing the port to open to the carb too soon. (I can't fix the crank). But I will do the head mod and see what changes. Thanks FL solutions was a good web site. (Wonder why I don't see Fox .74 in the magazine adds?)

vettdvr

Your problem sounds like a lean midrange. If so try running the main needle richer than normal and see it helps the transition. I don't think the Fox runs as well on a Perry as the MK series Fox carb. At least my Eagle I prefers the MK over the Perry. If you have one around see if it cures the problem. The carb may be smaller than stock, so if this works, maybe the new Fox twin needle carb would fix it.

A lot of Fox's have aggressive timing, but they are not the only ones. I have an older Super Tigre that is very trickey to tune for the same reason. A carb that has full adjustments works well.

I am a Fox fanatic. Sounds like the low end is rich. You should start by getting it leaned up. When fuel comes out the top of the carb on acceleration this is an indication of being rich. A god way to check if you are getting close is the pinch test. Get it to idle around 2,800 and pinch the fuel line shut. If the engine runs for a while without any change and then increase RPM's it is rich. If it immediately dies then it is lean. You should be able to pinch it for about 1 second before it increase RPM. This would indicate you are close. Then set the top end. I always set the low end first.

I have a new MK carb that has only ben bench run that I would consider trading for your Perry setup if you are interested. I had it on a Eagel 60 series I engine and it would transition as if it had an accelerator pump on it. The mods on flightline are good but I don't think they will fix your problem. More for flameouts due to overheating. Fox engines are typically high compression. Something else you might want to do is put a colder plug in it. This will reatrd the timing a bit. This might even work in place of modifying the head if you are uncomfortable with doing this. If you want to see a picture of the carb it is the one on my engine pictured on Flightlines under older engines 60 size.

Buy a decent modern engine, with a decent modern carb. The Fox
.74 may well be the biggest piece of junk ever sold.

MB.

Motorbrain:

Pull yur pants up. You're showing your butt again.

While I don't care for the Fox engine either, it's still a lot better and more reliable than a certain Asian engine that tends to blow its cylinder liner out the exhaust.

Bill.

Jim, I had a fussy .74 and cured it by countersinking the glow plug so that the entire idle bar was inside the combustion chamber, I have three of them now, two ringed and one ABC. They all three would turn a Graupner 12x8 two blade at 11,200 rpm, the ABC one is now a Diesel turning a Graupner 12x8 three blade at 9,400 and improving. The ringed ones ran much cooler than the ABC one when all three were glow.

I'd stay on this adventure. Fox's are often a diamond in the rough.

Sorry I don't have a fix for you, but the last one of these I sorted through for a fellow
modeler was a nitro issue...less nitro fixes much with these.

I like the cooler plug suggestion for some reason. It's easy...cheap and might
help you out.

Keep plugging away. Fox makes a good motor!

'Race

Hi,
I have several Fox 74's and have made extensive use of the Flitelinesolutions website
info. Absolutely essential to change head button to their design. Pay very close attention
to what they say about the later carb, and the groove in the crankcase. I have one engine
with the groove in case that would not quit with the carb completely shut. I prefer the
older MkX carb, I feel it has better midrange control of the mixture. I run 15% nitro
and 18% Castor oil.
Good Luck,
Jim

I got a new head button for my FOX .74 made to the button design on the Fliteline Solutions website.
What a difference. A DOG became a smooth runner. (Mine has the old 2 needle carb.)

Does anyone have the improved head button for the Fox .74 they would be willing to sell?
Thanks, Matt Mathison
[email protected]