w8ye

My Feedback: (16)

I always try out a repaired engine with an old used plug just in case something is going to go up and get on the element.

Hobbsy

My Feedback: (102)

Gary, to my knowledge the .50 and its .46 ABC derivitive never had any running problems. I have one .50 that is old enough to have a cold rolled pin holding the wrist pin in place. Maybe today I can take a close look at a couple of .50 head buttons.

earlwb

It probably means little to nothing. But for the heck of it, I ran some surface temperature measurements on the old Fox Blue Head .60 engine. I used a Infrared digital thermometer. Before I replaced the piston rings on the engine, it didn't mind running on a MA 13x6 propeller. But with the new rings it doesn't care for it much at all now. So I assume the compression went up significantly.
Anyway the top of the head at the base of the glow plug measurements are registering higher temps than expected, and I beleive that is the result of the head design being really thin in that area. The baffle plate on the piston requires a significant cutout in the head to clear it.

http://www.youtube.com/watch?v=mF_-8-EMsGE


and here is the engine being run with a 12x8 APC propeller. No temperature tests in the video, but the temps were around the same as for the 13x6 prop video above.
http://www.youtube.com/watch?v=kZ37eiSwsR4

Konrad

earlwb,
Do you have power figures for the before and after rebuild?

I liked how low you got the idle without a muffler! Is that carb one of those great Fox three mixture adjustment models? Could you have loitered a while at idle and still gotten a clean transition?

I have to ask, with the way those digital number dance all over the place, how do you know which is the real rpm value?

All the best,

Konrad

earlwb

The trees and the sunlight coming through seem to play havoc with the tach readings.
I wait until I get a high reading and assume that is good. Out in the broad daylight it works better. But I had made several engine tach checks before I made the video clips, and it was working out Ok then. it just went weird on me when I tried to make the video clips.
But yeah the flaky readings tend to make one wonder.

The engine has an exhaust baffle, so it can idle well without a muffler. I got it to idle as low as 2,000 rpm, but 2,200 or so seems to work better.

Yes it is the Fox three needle carb. Adjustments for everything.

When I first ran the engine it would run well with a 13x6 prop, but after the new rings, the compression went up and it doesn't like the 13x6 prop now. It was happier with a 12x8 though. I might try a 11x8 and see what it does, but I think the old 60's weren't setup to run faster than 10,000 rpms. I think i was running a 12x6 or 12x8 many years ago with it, but I forget now.

blw

My Feedback: (3)

You use a good quality tach! Try here: http://www.fromeco.org/products/05frctnc/default.aspx

I find it hard to believe that you don't know Andy Coholic. He has written engine columns for years. C'mon now.....

Konrad

I much prefer the analog tach. I'm looking for the RPM reversal point when I make my setting. I then record that number (needle position) I then richen the setting and restart the engine after it has cooled and bring the RPM back up to some pre-assigned RPM below the peak point. This is done to control hysteresis in the system. How often have you back off the needle only to find you had to back way off to get the engine to respond correctly.

But I agree a $30 tach is no match for $200 and up instrument!

And I still don't know Coholic. I don't read model mags, why should I they are for the most part just marketing tools. I also wouldn't be surprised that he doesn't know me. Did he fly FAI F3D Pylon or make the engines in the late 80's in the USA?

I too have been published in modeling rags. Do you know who I am?

All the best,

Konrad

earlwb

Thanks it looks most promising. But I still wonder if it is any good in the shade or not. That is my problem, in the hot summer 100 degree days, I really hate to test or breakin a engine in the direct sunlight. All the tachs I have work well in the broad daylight, but they tend to get flaky in the shade or worse just after the sun goes down and its getting darker.
The other issue, is if the new owners kept up the quality and vision of the original owner when they bought him out. Typically the new owners trash the company and ruin the products. apparently they didn't as when some parts were discontinued they discontinued the tachometer too. Then suddenly years later they start producing it again claiming it is up to the standard as before. Which is hard to beleive if they didn't have the correct parts when they quit making it.
Anyway, winter is coming and at the first freeze, the leaves will all fall off the Oak and Elm trees and it won't be quite so shady then.
I tend to get pretty disenchanted with various electronic devices, everything seems to not work as advertised anymore. The marketing types keep over-hyping everything.
the Glo-Bee tach works pretty good in the sunlight. my old Hobbico tach worked OK too, but the stupid batteries are amazingly expensive for it and it uses them up fairly fast. I still wish I had my old heathkit analog optical tach I built years ago. Even if it wasn't good except in direct sunlight.

I guess I can come up with a testing harness and sensors for a Datalogger tach option. Humm, maybe I need to make my own tachometer or something. Of course maybe one of those German or Austrian mechanical analog tachs will show back up for sale at a good price one of these days. I still kick myself for not buying the last one which was new and unused and complete in its wooden case when I could have gotten it.

earlwb

To tell you the truth, I do not know Andy Coholic either.
I do not remember reading anything from him before.

But then heck, I do not remember reading anything from Konrad in the magazines either.

I am a published author of a number of magazine articles too. But it was for computers and software years ago. before companies you worked for made everything you do, their property instead. I seriously doubt anyone that might have read any of my articles remembers me either.

I would like to know what the "bolt" is in a carb too. I never heard that used for a carb before.

OK I looked at the website, and they need to work on it, it is terrible on a MAC machine. So since they said it "works in any lighting conditions up to six feet away", I'll take a chance and hope it wasn't a waste of a $104 dollars to find that out.

Konrad

I had some of my words published in MAN and FLY R/C but on the subject of aircraft and as a reviewer of some aircraft kits. I'm sorry if I left the impression that I was published on the subject at hand. (I tended to keep the research to myself or to those that might have the background to understand it and hopefully correct any of my false assumptions)


All the best,

Konrad

w8ye

My Feedback: (16)

A few years ago Andy Coholic was a regular contributor in this thread. He is still a regular current contributor to RCU but posts in various areas.

http://www.rcuniverse.com/forum/sear...olic&top=20000

earlwb

I remember reading posts from him here in RCU now. I remember thinking what a great guy he is. The name just never stuck at the time.
Thanks for the info.

Konrad

Thank you,
I think you had shown this before. I was responding the query made by the other moderator. Now who was he?

All the best,

Konrad

Hobbsy

My Feedback: (102)

Earl, the Fromeco works in the shade, the only problem I've encountered is that its very difficult to get the tach numbers to show up in a picture tis time of year. These pictures were both taken under the roof where I store my wood and run engines. Picture #1 is a morning Picture, #2 is fall afternoon.

WMB

My Feedback: (1)

Hi all, One of the guys in the club has a .70 something Fox. The exhaust has a rotating plate in it that reduces the area for exhaust flow when the carb is at the idle position. He did find a muffler to quiet this beast down. He is having all sorts of problems. One thing that needs to change is the fuel tank position. Once he gets it mounted in a better spot, can he ever expect this to be a reliable engine?? He builds some unique models, hate to see him loose one due to a poor running engine.
thanks, MikeB

earlwb

He likely has a old Fox .78 or has a old Fox .74 engine. yes they can be very reliable. These Fox engines are all high compression engines. As such you use little to no nitromethane in the fuel. Many people run into problems when they try the 10%, 15% or even 20% nitro content fuels.
You also need some castor oil. The .60 and .74 engines both have needle valve rods (but Fox might have changed it out to a bushed aluminum rod later though). A new engine can be quite tight, and need a patient and considerable running in before it starts to work good. Fox tended to make the engines tight at the factory. originally we only had castor oil based fuels back then, so the engine prefers castor oil in it. I have good luck using Omega 5% nitro fuel with a blend of synthetic and castor oil. The .74 and .60 engines of this era because of the needle valve rods, did not need 20% oil in the fuel, so you do not need to add extra oil to it per se. But maybe some extra oil during break in is a plus.
Also except for the .78, these engines do not rev up all that high, so you may need to prop the engine accordingly. 10,000 rpms is probably max for them. I forget what I used to run my old .60 at many years ago. But maybe I'll find a old engine review article about them eventually. But way back then no one owned a tachometer anyway.

The two needle carb is adjusted by getting the engine to run on the rich side, goto idle and adjust the idle needle, and then go back to the main jet and adjust it. usually once you get the idle needle set you will never have to touch it again.
The three needle carb can give some people trouble. Adjust it enough to get it to run on the rich side. Then you go to idle and adjust the idle needle (the one with the fuel fitting) to get a good idle. Then adjust the mid range needle to get a mid-range that isn't too lean but not too rich. Then adjust the main jet. With the engine you'll need to set it a little more on the rich side off of peak rpms. If you don't have a all castor oil fuel, don't try going for the peak rpms and then back it off unless the engine is well broken in. Way back then we didn't use muffler pressure. So the fuel tank sat higher and closer to the engine. The engines were run a little more on the rich side as they tended to lean out in the air as the fuel tank emptied.

Oh yeah, unless the muffler is reasonably free flowing, you need to remove the baffle as it may be too restrictive with both on it. But it depends. Fos used to make wrap around mufflers that sealed up the holes where the exhaust baffles went through. Streamline used to make clamp on mufflers and included a couple of aluminum plugs for the baffle holes when you used their muffler on the engines. I have one of their flow through mufflers on my .78 engine too.

earlwb

That is funny, I had the opposite problem lately. the Infrared themometer has a backlight that tends to drown out the digits using a video camera on it.
But thanks for the info, I think I'll like this tachometer.

blw

My Feedback: (3)

Yep. It looks bad on mine too. I guess they didn't put a lot of time in testing the website.

It does work well in most lighting. You don't really have to worry about the sun being in front or in the back. You can hold your model with your ankles while running it and tach the prop. Mine gives consistent numbers.

I don't miss holding the analog tachs about an inch from the props and hoping for ballpark numbers.

Konrad

The modern analog tach use much the same sensor as high end digital (actually better as we are often willing to pay more for these custom built units). It is just in how the information is presented. The ability to instantly see the RPM reversal point gives the analog read out its advantage over the digital read out. What sensor (tach) do you know that needs to be within an inch to pick up the props signal?

All the best,

Konrad

Hobbsy

My Feedback: (102)

The Fromeco/TNC works very well from inches to several feet away. farther away requires better aimin.

landeck

My Feedback: (1)

I have used many tacs over the years. The best analog tac is the Ace TachMaster II. I still use it from time to time. But the best overall tac is the Fromeco/TNC digital tac. It is the easiest to use. For finding the peak it has a great feature in that it displays the peak and current rpm at the same time. In that way you can see when the rpm's start to fall off.

Bruce

1QwkSport2.5r

A little off the subject that has been talked about.. I have a Series 5 Fox .40 single BB engine from 1983. I've been trying to get it to run on the stand and failed to get it to run properly. Recently the engine ate the glow plug element (not sure way it melted, it didnt run long enough to lean out and burn it up) and a chunk got between the piston and sleeve thus scoring the sleeve pretty good. I would like to send this engine in and trade it for a brand new one but I wanted to find out what everyone's thoughts were on the .40 STD BB engine versus the .40 Deluxe ABC version. Fox says the only difference between them is the ABC Piston/Sleeve in the Deluxe. Is it worth the extra $20 for the ABC?

I will note I don't fly planes - I originally planned to build a hydroplane airboat for this Fox .40 and I still would like to build it, but I need to know which engine I should get. I know almost all R/C Car engines (what I'm most familiar with) are ABC and break-in fairly quickly but I'm not opposed to a longer break-in if the performance is the same between the two.

earlwb

For an airboat, I would just go with the ringed version. I doubt the ABC version would gain you anything. But if you wanted to use the ABC version go for it.

Sometimes when a engine is first run (or after being laid up for a long time or rebuilt or repaired) they'll eat a glow plug or two. I usually use my old used glow plugs at first, instead of a new plug, in case it happens. But the oils in the engine, tiny metallic particles becoming airborne as the engine runs, etc. can all have an effect on a glow plug. Plus sometimes it is just bad luck.

What fuel were you using in the old Fox engine at the time the glow plug melted on you?

Anyway when I have a balky engine that isn't running right the first thing I try is a new glow plug, so I put the old plug in my "used but maybe still good box". so over the years I wind up with a fair collection of them. So I use them in a engine when I need something to test with.

Sport_Pilot

The Fox ringed engines take longer to break in than other brands.  If you have problems with breaking in engines, and starting stubborn unbroken engines, then go with ABC.

1QwkSport2.5r

I was using SIG 5% nitro/20% oil and an MC59 plug. I bought a Fox idlebar plug, and I tried a Mecoa hot plug. The MC59 plug gave me the best run. I started with a used mc59, tried the idlebar plug, tried the mecoa plug, then back to the 59 plug. The engine came to me disassembled. I checked the sleeve and piston to see if it was out of round or not. Both were round and the fit was nice. The liner has a "crud" line at TDC where the bottom of the head button sat - this was castor residue that came out with denatured alcohol. The engine had really good compression and popped nicely but wouldn't start and run consistently. Oftentimes it started in reverse and would die. The few times I got it to start in forward (CCW) it ran really rich.


I have no issues breaking engines in. I've broke in a dozen or more engines mostly all ABC. More recently, an AAC K&B Sportster .65. Never had any issues with new engines, only used ones and this Fox being one of the few used engines I've ever acquired. I would rather stick to ringless engines, personally.

I don't care how long it takes to break an engine in. I just want one that will last a long time and perform well (or better than the imports). Does the .40 STD use an iron piston/steel sleeve like the old ones or are they nickel plated sleeved/alum. pistons? I heat cycle my engines using the mildest fuel they will tolerate with lots of oi