A question for those with Fox engine experience

I would get the tilt up muffler since you don't know which model your going to use the engine in. Fox engine require a prolonged breaking period. Once they are properly run in, they are strong and reliable. Most complaints you see about them are from people who have not fully broken them in. I say almost two gallons worth of fuelI have two Fox .15's and after they were broke in, they are screamers, Very good engines.

I think Vance has it right. Here's a site out of Canada by some folks who know a whole lot about Fox engines!

Not knowing what type/style of airplanes you are going to put them in, flip a coin.

I found that site and bookmarked it shortly after I bought the engines. I'm wondering if I would have bought the engines at all had I seen that site first.... ;-)

Good flying, desmobob

That was my initial thought, but then I wondered if one was the "standard" and the other was for unusual mounting requirements. I can't seem to figure it. I guess the tilt up model would be good in models with a cheeked nose instead of a cowl? But why the tilt down? Since I have three of the engines, it certainly wouldn't hurt to buy one of each type. (It would just hurt my wallet....)

Good flying, desmobob

Congratulations on your engine purchases. Those are very good engines. But like it has been stated here -- they do require a long break in period...why some older ones are better buys than new ones.

Those BB engines run good. The "tilt up" mufflers are really "tilt out" mufflers so when the engine is mounted on beams and the cylinder is mounted horizontally.

They got an undeserved bad reputation when engines came on the market that didn't require a break in period and so seemed to be more reliable. I have seen guys crank and crank on a new Fox in a model. He was cussing it while others were telling him to dump the engine and get a "good" one.

These modelers were the new generation of modelers who wanted everything to work right now with no investment of their time in learning or breaking in.

The Fox engines were/are good engines when treated like Foxes were designed to be.

Ken

I've had good luck with Fox engines if they are broken in correctly. Two gallons rich running on the test bench is not unusual for a fair break-in. You can also motor the engine on a drill press with a half gallon of Marvel Mystery oil fed to the carb and the needle adjusted for a very light oil mist out the exhaust. Run the press at 1800 rpm or so for 24 hours and when you are done you will have a 1st rate engine that will run forever or until you crash it.

I don't mind long break-ins. Sometimes (like today) I get in the mood to put an engine on the test stand and let it run. (I broke in a new RCV 91CD today.)

TWO gallons? =:-0 Now that's a l-o-n-g break-in! Are you suggesting the engines aren't suitable for flight until then? Yikes!

Now that is an interesting approach to the problem....

Good flying, desmobob

"Shenanigans! Shenanigans! Grab your brooms!"

I do not see how the drill press can give the temperature cycling a break-in gives, but it will wear away the surfaces as they should but not with the same fit. Thermal expansion will be different for different parts of the engine.

Ken

Gentlemen! Gentlemen! What is all this about long brea-kin periods of Fox engines? I don't know if Fox still offers it or not, but they sold a fine powder that one mixed with a bit of fuel and applied through the intake venturi for a faster break-in. May still be available...' I used it on a Fox 45 I bought many years ago and that little gem is now on my second Four Star 40 and will take the plane straight up.... broke a crankshaft on it about ten years ago and Fox replaced it for small change and it still is running very strong..... Other commenters are correct...take time to get it right and that old Fox will run on and on and on and on... Frank Schwartz

I have always considered the end of the breakin the point at which it delivers peak power. In which case two gallons would be only a little more than average. Modern Fox's don't require the long break in that the old ones did. They use CNC machining now and tolerances are better. They no longer set them up extra tight and lap the rings in. But they do use hard metal and the ringed engines do take longer to break in than an OS.

All three of my brand new Fox engines were made in the mid-eighties; pre-CNC, I'd guess.

Good flying, desmobob

That sounds interesting. I have a selection of superfine powdered abrasives an old Corning Glass employee gave me for the purpose of fire-lapping the barrel of a troublesome rifle I have. I don't think they'd be suitable for the Foxes, though.

I wonder if there is a common abrasive that's harder than the Fox cylinder bore, but softer than the bearings? Not that I'd use it....

I'll play it safe and give one of the .40BBRCs plenty of test-stand time, then I'll put it in a high-wing model to finish the break in. After I order a muffler. I think I may keep the other .40 and the .36 as conversation pieces, or if I really like the way the .40 runs, just the .36.

Good flying, desmobob

Good old Lusterlox. A bit more aggressive than Tin Oxide, IMO

Back in the '80's, that was a 'behind the counter' item at the hobbyshop.

Only sold it to those with a clue, as anyone who thought 'a Little is good, More is better' got bit hard by Lusterlox, and got to use Duke Fox great policy on getting parts on his motors afterwards.

My Enyas seemed to take as long to break in as the Fox, but the airbleed carb on the Enya made them more Newbie friendly than the Fox

If you mount the engines straight up, use a tilt up for low or mid wing and a tilt down for high wing. If you side mount, use a tilt up to get the muffler away from the fuselage (less gunk!).

Their mufflers all have rear exits so a deflector may help.

The compound used to speed break-in was known as Lustrox.

Ed Cregger

I have seen more than a few folks break-in and then break-out their engines using Lustrox. Pity. But I had to smile.

Ed Cregger

No. I think Fox's were CNC since the 70's. I remember buying a Stunt .35 in the late 70's and was suprised it didn't get real hot on the test stand and take a gallon of fuel before it would four stroke at a reasonable temp. But I could have just gotten lucky. But IMO its that people keep repeating stuff from when Fox was popular in the 50's and