RE: OS 46 SF ABC
 

Well, you make some good points. However, the whole idea behind "operating temps" is the fact that dissimilar metals expand at a dissimilar rate. Non-ringed engines get compression by a slight taper at the top of the bore; if the liner does not expand fast enough to accomodate the piston, the piston WILL be "squeezed", stressing the connecting rod and its pivot points.

I have no doubt yours and downunder's "tests" produced the results you claim; I have run several ABC engines that way back before I heard about the best way to do it. As a matter of fact, the ABC .46 SF and ABC .40 SF I alluded to above were "run-in" via typical ringed engine methods; and they both served me well for many years. I never stated that doing this would result in a trashed engine. However, I see where one could infer that from what I wrote. So, I'll grant the point and change my statement to "Do what floats your boat.";)

But I still believe that four-cycling a new non-ringed engine is not the best way to break it in. High spots on the piston, etc., do not enter into it AFAIK. Agreed; that particular problem is taken care of by friction, and with sufficient lube is not an issue.

And I also do not see where this discussion has been the least bit adverse.

RE: OS 46 SF ABC
 

Hey, that's a good thread. Plenty of good reporting of experiences. Of course, I only read the first few posts but what you found matches up with what we found over the course of a couple of years of dinking with timing etc. BTW, I worked for some years in hobby shops while working my way through college (you could do that back then) selling those early engines... and taking some back that'd broken... and rebuilding some... etc etc but seeing TONS of them.

RE: OS 46 SF ABC
 

Brian,


Some engines, notably from the former USSR, were claimed by their manufacturer, to last for 4 (four) hours.
I currently have two ABC engines (guess from who), that have 50-70 hours on them.
From their current TDC pinch, I can conclude they have no intentions of 'going south' very soon.

From a thread in this forum, I calculated that a certain OS.50SX, lasted only about 30 hours, before its ring needed replacement.

And generally, most low price ABC engines available today (mostly from China) are so loose to begin with, there is absolutely no chance they will ever be damaged, even if broken-in with the needle open 8 turns and the glow driver on....

And yes, I may have 'over-leaped' with my designed life expectancy numbers...100 for those older engines and 15...


Darock,


Those broken con-rods George Aldrich (and Clarence Lee) mentioned, were destroyed by what the slobbery rich break-in causes (and it really does cause this); tension-compression cycling.

In a two-stroke engine, running at a consistent two-cycle, the rod is never under tension.

Whatever you and Brian can say, cannot change this fact; in a very tight, tapered-bore engine, running at a cold four-cycle, the piston does catch in the sleeve at TDC, on non-firing strokes.

In fact, it catches strongly enough, for the oil film to be broken and for compression not to be enough to dislodge it, so the rod must pull it out.

This is the only possibility for a strong tensional force to be applied to the rod in this type of engine.

Need I say again tension-compression cycling caused rod breakage?

Also, the highest RPM two-stroke engines mostly damage their rods during break-in.
How could that be, when they normally run at 30K, after break-in?

'No four-cycling' is the obvious answer.

And, BTW, I am only 43. Not that old...

RE: OS 46 SF ABC
 

What type of modern engine would be that tight? It can't be sports type engines other than the small Norvell's which I believe need a very special initial running in.

As for the OS 50SX, I'm not sure what your point was there but if you're saying it was worn out in 30 hours then it must have been very badly mistreated. Give me a Jett, Nelson or whatever and I could ruin it in about 30 seconds (and not with a hammer either :) ).

RE: OS 46 SF ABC
 

Brian,


GMA and Clarence Lee's experience was with K&B F1 QM engines.

They broke the rod very frequently.

I agree most current engines, with the exception of Jett, Nelson, Profi... are not like that.
Yet, the ABC break-in is still done correctly and very quickly, my way.
I had no failure yet.


About that SX; the person who entered that thread, according to his own description, seemed to be running this engine very sensibly, with a commercially available fuel, which is not considered junk (or was it Cruel Power?...).
The ring lasted only 6 gallons, if I remember correctly.

RE: OS 46 SF ABC
 

Profi...recommended to be run in at a 4 stroke (at 26,000 revs :) ) as per http://home.kabelfoon.nl/~fiorimet/Index.htm
Jett...open the needle an extra 2 turns from the factory setting.

BTW, I'm not saying your way is wrong so long as it's not set too lean. The safest way to ensure it's not too lean is to start it quite rich and if it's 4 stroking then it won't do any harm and you can take your time leaning it out a little to get the correct mixture which would be at or just above the point it breaks into a 2 stroke.

That SX was either faulty or run on Cruel Power (or something similar). My ST G51 kept getting better and better for about 15 hours then settled down.

RE: OS 46 SF ABC
 

Brian,


I somehow knew that Profi break-in instructions will come up, as would the Jett break-in procedure.

Over a year ago, I approached Jett's Robert Brassell, asking him about this issue, of 'four-cycling' their engines for 1 minute, before it is leaned down.

Bob wrote that most Jetts, like other very high performance engines (I guess Profi would also be included), with radical timing numbers, cannot ever be made to 'four-cycle'.
At least not in the sense that both you and I perceive this term; the way a properly adjusted control-line stunt engine runs at level flight attitude, actually firing on alternate revolutions (Someone brought an article here in the past that proves this really happens, I believe.).

Randy of MECOA, in his [link=http://www.mecoa.com/faq/breakin/breakin_abc.htm]ABC engine break-in page[/link], mis-interprets this term ('four-cycling' to him is just slightly rich of 'peaked' and is still leaner than 'rich running' and much leaner than 'sloppy rich running').


Do you think Profi would tell you to 'a cold head, as rich as possible, just barely running with the glow driver attached' break-in?
I doubt it... You can see in the photo that MB engine is spewing out smoke, not a mass of raw fuel.

I believe Profi might be interpreting 'four-cycling' as Randy does...

RE: OS 46 SF ABC
 

Whatever you and Brian can say, cannot change this fact; in a very tight, tapered-bore engine, running at a cold four-cycle, the piston does catch in the sleeve at TDC, on non-firing strokes

Dar, I don't know about Brian, but I'm not trying to change fact. But truth is, there is a world of difference between theory and production realities, and production realities is what I'm trying to address with my recounting of what I encountered. When I worked in the hobby shops, the job was perfect for my interests at the time. I saw a BUNCH of engines. We'd get a dozen K&B Torpedos at a time. I was ordering piston/sleeve sets for OS .35 stunts about once a month during the summer. I carried piston/sleeve and conrod sets for almost all the popular engines and especially for the rat racing engines.

I was miking almost everything that came through the place if it was something that didn't require tearing down to measure. Almost every engine that came through got a prop stuck on it so I could turn it over to check the con-rod fit and the "compression".

Back then (bear with me here, I'll get to "nowadays" next) engine parts weren't CNC'd. And back then, most engines were hand assembled by short timers who were undobtedly making minimum wage. Let me state right here, that I'm not talking about the theory of ABC or ringed engines, not talking about theory at all. All you guys are dead right, spot on, about the theory stuff. But back then, the assemblers had a pile of pistons on one side of the bench and a pile of sleeves on the other. Theory was that they'd make as good a match up as possible. Truth was that they put stuff together that would go together and their biggest hope was to make their production quota.

You can not believe the wide range of fits that came out of the factories. For the most part, over the years I could handle (fondle?) those engines and parts and measure them, there really wasn't a mfg who was consistently good, nor a mfg who was consistently bad. Most people would be amazed to have seen how many pistons weren't round and how many sleeves weren't either.

What I was trying to get across, and didn't do very well, was that theory is great for discussions and the printed advertising that goes on the engine box and in the magazine advertisements, but it didn't actually always apply to one or two engines that an individual modeler could afford to take home and run.

What George and Glen wrote about was what they saw. And they saw a different mix than the guys running hobby shops saw. And the guys behind the hobby shop counters saw a lot fewer broken con-rods than the guys writing engine columns or doing Dubby Jett type hop-ups.

I would hazard a guess that far more taper bore engines were broken in the "safe" way than were broken in "properly" back then. Most guys buying those engines were digging into the family funds to get their hot new engine and were actually a bit afraid to risk the sucker. I saw hundreds of Fox .36x's go out the door and that one had a bad reputation for blowing up. I was marking the boxes of all of them our shop received. The ones that looked bad to me were often the ones that broke a crank or rod.

As near as I remember, I've never seen or heard of an engine that broke a crank or rod in break-in. Theory says that the worst "piston being grabbed by the sleeve because of cold running" would come from the initial running, when the fit was tightest and when the engine was being broken in. And nobody I knew then tried to fly combat at a rich 4-cycle or rat race a slobbery engine. And that's when the suckers broke. And near as I can remember, a bunch of guys broke in their engines with at least one sloppy rich run to begin with.

Now, is it possible that the break-in weakened the rods? Sure. But I knew guys who swapped rods after break-in and after so many cycles. It was standard practice for most of the hot combat pilots and fast rat racers to tear down and rebuild every so often. And they broke new rods as often as other guys broke "original" ones.

When I bought my new OS .46ax engines a couple of weeks ago, I did them the same way I'd done so many engines back in the 60s and 70s. I stuck a prop on each of them and turned them over. I've got to say that today's manufacturing is excellent. And all 4 of those engines felt almost exactly the same. And I think the chance that any one of them would seize during breakin is about zero. And theory says they won't want to stick a piston after they're actually run warm enough to wear in.

What I tried to say in too many words, is that theory is great for discussions and advertising, but don't get so excited about it that it gets in the way of personal observation, and don't go overboard and try to apply it as gospel that covers everything.

RE: OS 46 SF ABC
 

......this fact; in a very tight, tapered-bore engine, running at a cold four-cycle, the piston does catch in the sleeve at TDC, on non-firing strokes

Think about it for a minute or two...

What actually happens during break-in? The parts that are in interference "wear in". What is "wearing in"? One part or the other's "high point" breaks away, or chips off, or is burnished down. Isn't most of that the result of "catching"? Some of it? Yup...

Hey, you guys enjoy your debate. I flew my Phoenix .46 Sukhoi for the first time yesterday and plan to fly the sucker today as soon as the sun comes up. (Hey, retirement is hell but somebodys got to do it!) And that OS .46ax is running like a BEAR. I'd hazard a guess that it's stronger by far than the .60s of my youth. Ain't modern technology grand!

RE: OS 46 SF ABC
 

Darock,


With today's CNC production, with batches of a thousand pistons and a thousand sleeves, you take any of each and they all fit the same...
With current CNC, there are no 'high points' as old production techniques produced; so only a 'burnishing' is needed to make the fit perfect.

And as to power, reading old engine reviews in MAN magazine, current engines spin a given size prop at about the same RPM as did Schneurle engines from the past.

I take OS as an example; the FSR and the AX/FX, spin props at about the same RPM, but current engines are less noisy doing it.

But even when 'freed' from the quiet muffler, no real power advantage results in the new engine.


It is strange that one of the power paragons of those days was the K&B 6.5 cc RE ABC engine, which had a P+L set similar to their QM engine, which was notorious for stretching its rod, until it broke... during, or shortly after the "safe" break-in.

RE: OS 46 SF ABC
 

I have an OS .46 SF that I now have in a Sig Skybolt which I use to have a K&B .61 in. I have had the engine for 10 years and have run it in other planes. It has excellent power and has been among the most reliable engines I have ever owned. To me it is a better engine than the relatively new OS .46 FX that I also have.
You will be very happy that you were able to acquire it.

RE: OS 46 SF ABC
 

The real situation as I see it, after seeing hundreds of engines broken in and used, is that back when all our "facts that everyone knows to be true" were originated, tolerances back then basically muddied the waters. Yeah, the facts were true... somewhat... but I'm certain that a bunch of our broken rods came more from out of round pistons, or out of round sleeves, or way over tight piston/sleeve combinations, or off-axis wrist pins, or under sized wrist pins, or bad con rods or whatever causing the seizing to occur.... the problems were more from out of tolerance than from the theory that "everyone grew to know as fact."

And today, our tolerances are such, and our metalurgy is such, that some of our old truisms just aren't going to be as true as they were. And some weren't very true back then.

But whatever....

I'm happy with whatever you guys accept. In spite of the wind dying down somewhat today, it started raining so I had to work in the shop and got a bunch of things done on the new Ultimate. That sucker is going to be sweet. And tomorrow is supposed to be clear so the Sukhoi will get some more trim flights. Life is good.... :D

RE: OS 46 SF ABC
 

It is not possible for the piston to "catch" in the top of the bore on non firing
cycles when an engine is fourcycling. This is simply an Internet myth, plain
and simple. :eek:

The reason some of the K&B racing engines broke the rod is because they were
too tight....not because of the way they were run-in. This over stressing of the
rod caused some immediate failures....others failed in a short period of time due to
the abuse the rods suffered in the first several seconds of operation.

FBD. ;)

RE: OS 46 SF ABC
 

I wish I could tell how an engine was tuned by looking at a photo :D

OK, here's my OS 40VF in different stages of tune in a similar size and positioning to that MB. I varied the tune from almost peaked to sloppy rich 4 stroking to just on the 4-2 break. Tell me in which one it's pouring out masses of raw fuel.

RE: OS 46 SF ABC
 

Brian,


I guess you got me on that.

In the last several years, I have only broken in ABC type engines, with the exception of my own MVVS 26 cc.

I remember the smoke of the 25% oil, just above the 2-4 stroke break, but don't recall exactly what the 26 cc spewed out, on less oil and a four-cycling setting.


The photo in the middle seems the richest, followed by the right. The left seems the leanest, but the differences seem too small.

Photos can't seem to replace an actual view... and since there is no sound... I guess this guess was misleading.

RE: OS 46 SF ABC
 

Even I've got trouble saying which is which, I have to refer back to the original photos because I know the order I took them :)

The left pic is right on the 4-2 break, the centre pic is almost fully peaked so naturally the right hand pic is an extremely rich 4 stroke.

RE: OS 46 SF ABC
 

I have a 46SF ringed engine. It just purrrs, but does not seem to put out quite as much power as the AX/FX series. Were the ABC (ABN) type SF's any more powerful than the ringed versions?

Thanks,

Ernie

RE: OS 46 SF ABC
 

My experience is limited to the .61 SF. This engine was designed when everyone wanted slower turning, but powerful engines. The SF certainly accomplished this in spades. While the one that I flew did not "scream" as previous OS .61 engines had, it pulled the pattern ship that I was flying in grand style while turning a 12x8 propeller. I would think that the .46SF was designed along the same lines - that of pulling more prop at a lower rpm. The .61SF really shined when pointing the nose straight up. I was extremely impressed with the power and the much quieter sound level produced by the engine prop combination.

I would look for the .46 SF to be set up similarly. Forget the noise, think in terms of pulling power.

RE: OS 46 SF ABC
 

If it is so wrong why does my OS .46AX manual tell me to on the first tank of fuel to run it 4 stroking? Then after a few minutes tune it to just on 2 stroking for 10 seconds and then back to 4 stroking for 10 seconds. Repeat this procedure until the tank is dry. Then it tells me on later flights to just run it bordering on 4 stroke but 2 stroking. As each flight goes by it says to lean it out further.

You are talking about breaking in a ringless engine yes?

RE: OS 46 SF ABC
 

Panzerd,


Read [link=http://www.osengines.com/faq/product-faq.html#q2]this reply in the OS Q&A[/link].

Your FX manual was generically written and no one at OS thought it would be beneficial to update it, for the sake of the owners of ABN engines, made by OS.

...No one cares if your engine wears out after 10-15 hours, or lasts 50, or more.

If it wears out quickly, more spares are sold... No?

RE: OS 46 SF ABC
 

OS are loving your money, and you buy new engine or spareparts from OS factory..[8D]

Jens Eirik

RE: OS 46 SF ABC
 

OHHH NOOO, do you think I have done any damage? I have only run is once using the method stated in the manual.

RE: OS 46 SF ABC
 

Downunder: Even I, a relative novice, could glean the distinction in your two answers. In America we complain about women bickering over nothing: Pole vaulting over mouse turds. But some of these guys on the internet bring a whole new meaning to the concept of arguing over the most inconsequential issues. What amazes me is that they accomplish this feat with the written word. Also, it really appears as if some people have history...bad feelings. Jim

RE: OS 46 SF ABC
 

Panzerd,


...Probably, no immediate damage occurred, but as the Q&A state, it is not really good for the engine.

I believe that even after the passing of the creator of OS (Oshigawa?), this big company should still give its customers the better advice, in manuals printed for each type of engine, instead of one manual for both ringed and non-ringed engines (FX, AX and SX), which unlike the manual printed for Super Tigre engines, does not differentiate between them...

That's the way to promote wear and sell parts...

...At least the Q&A show there is someone nice there...



Jim,


I did not exactly understand what you meant there; especially the last part..., but Brian (downunder) and I often argue over these pages.

I am not sure who enjoys this more; us (at least me...), or other onlookers...

Each expresses his side of the truth and his ideas. This is the point of being it these forae.

RE: OS 46 SF ABC
 

panzerd18,
Nah.... You haven't. Matter of fact you've very safely insured that the engines weren't hurt with lean runs too soon in their lives. With the exact tolerance they're making those engines nowadays, nothing is going to seize or grab.

I've just broken in the 2nd .46AX and did the same rich 4cycle deal. Either one of them could pull a Humvee out of a ditch if the Humbee's wheels would roll, otherwise they'd pull the front bumper off. If my rich breakin hurt them, I'd really hate to think what they'd do otherwise... maybe pull the firewalls off???

About the only negative about running those motors too rich a 4cycles is that you're just wasting a slight portion of that fuel. They obviously will break in better on a "just into 4cycle" setting than they will on a "very rich 4cycle" setting.

As for the myth that OS engines are being produced for short lives nowadays.... bwahh ha ha hahah I fly with a bunch of guys that I'd bet are just like almost every r/c field in the US and I don't think but a few of them have ever worn out an engine through use. And a couple have OSs that've had gallons and gallons and gallons run through them. And the newer OSs look like they're going to run twice as long as the older ones. Ain't nothin' about OS that even hints of "short term".