New way to temper McCoy Red Head pistons

Use Testors McCoy engine crankcases for barbeque briquets? Now there's an idea.

Thanks for that George, all kidding aside I wouldn't mind a re-worked McCoy using a later PC assy. They are a pretty engine.

Cribbs74 wrote:Thanks for that George, all kidding aside I wouldn't mind a re-worked McCoy using a later PC assy. They are a pretty engine.

Not mine. I've stripped the paint off the Red Head and am leaving my engines in bare aluminum. Plus, I've now got Evolution 40/46 remote NVA's on both mine. One flier told me that doing such was unthinkable, like a day without sunshine. But I did it so the engine would run cooler. They actually run decently, only thing is being careful with the right fuel, right prop and avoiding lean runs wherein possible.

But you're right. A lightning bolt crankcase (cylinder liner has several bars across the exhaust opening to hold piston ring in place) and Series 21 piston with ring, or chromed piston would make a lasting engine and overcome metallurgy problems.

Next time we get a chance to fly together, I think you will see a different running engine. And that Fox .35 Stunt you gave me, I'm going to put that in my Sterling profile Hellcat build.

I kept waiting for a punch line. Sounds like instuctions on how to ruin a McCoy the fastest way possible. I dont know!
I did hear this one somewhere. If you have a McCoy with low compresion, get if running on fuel with a all castor lube package, 26% minimum. Get a wet two cycle needle on it and take a previously fabricated shield and slip it over the cylinder and head untill it smokes then lift it off. repeat this untill the compression is good. I dont know!
My McCoys have great compression and seem to stay that way.

GallopingGhostler wrote:...And that Fox .35 Stunt you gave me, I'm going to put that in my Sterling profile Hellcat build.

George, when you get it looking like an airplane, be sure and post some pics. Thanks to Ron I have an interest in Sterling kits. I'd love to have a Mustang to accompany my Yak-9.
Rusty

Normally you would do this piston swelling and castor build up during the running-in of the engines. That is what the heat cycling is for. You end each of the short runs by running on the lean side.

I guess if someone were to never ever lean out their engines they might manage to see some gain later on instead...

I was a little surprised to see that the thread was started in the beginners forum (!) on RCU, apparently it takes more than +50 years to be accepted as a regular hobby flyer?

Surfer_kris wrote:Normally you would do this piston swelling and castor build up during the running-in of the engines. That is what the heat cycling is for. You end each of the short runs by running on the lean side. I guess if someone were to never ever lean out their engines they might manage to see some gain later on instead...

Due to flier impatience, many engines are or were broken in on the aircraft. Also due to impatience, some thought that using a large fuel tank and letting a new engine run for 20 to 30 minutes at a time was good practice, when it is not. And you are right, one gains better benefit by short runs and the heating cycle. This is why I use a 1 oz. fuel tank. Engines break in quicker this way.

It's when manufacturers realized this and went to ABC / ABN technology and more precise machining, that long break ins were no longer necessary. This is why you hear many nowadays exclaim to encourage fliers like me to dump the old technology and buy an ABN Schneurle. It's not that the newer technology is bad, they just don't seem to understand what it took to do an acceptable break in.

I was a little surprised to see that the thread was started in the beginners forum (!) on RCU, apparently it takes more than +50 years to be accepted as a regular hobby flyer?

Donny who started the thread, later admitted he posted to the wrong forum. What he didn't realize is that it stirred such an interest that it has become quite long a thread. "Clubhouse" would have ben the right forum, but personally I rarely visit there, so in a way it was posted in the right forum. If you think about it, the more experienced fliers like to mentor younger fliers, so in a way posting there reached the right audience.

AFAIK the manufacturers did not just switch to ABC, it was an advancement in technology. The first (real) ABC engines had a very tight pinch at the top and probably just as many folks ruined the fit using a slow, rich break-in as did ones using iron/steel did by not using proper break-in. Even the engine expert George Aldrich admitted he ruined the fit of his first ABC by lapping it for a looser fit at top end.

The original way to break-in an ABC was to get it up to full running speed ASAP and run it just on the rich side of peak. Using slow/rich running would put undue stress on the conrod bearings and could wear out a conrod in a single rich run. Through the years the ABN engines apparently allowed a closer match for expansion between the high silicon aluminum piston and the ABN cylinder, thus current break-in procedures.  

Iron/steel on the other hand should be run rich/slow for a couple of runs then heat cycled with a slightly rich one or two minute runs, followed by cool down to ambient temperature. Of course if at any time the engine starts to sag (slow down), immediately shut it down and let it cool.

Running a NEW iron/steel over-lean with low oil content can cause thermal runaway which usually decreases the overall life of an engine. My guess about that McCoy is that possibly since it was already over the hill, it merely formed a castor varnish as mentioned above. This only works for all-castor fuel and running synthetic will remove the varnish. Another possibility, and what you are shooting for, is that the piston grew from the extreme heat. If doing this, I would rather do it on an engine test stand where I can control it at any time. Shutting off the engine during iron/steel break-in should consist of pulling or pinching-off the fuel line so the piston will cool naturally.

Of course these are only one way and we all know other ways work. Good luck with yours.

George

Oh, I guess sometimes I get myself into trouble by surmising my thoughts, which are more talk and opinion rather than a straight distillation of facts. Couple this with my non-pertinent engineering background (got a BS in mechanical engineering and you know what BS means , worked initially in aerospace aircraft structural testing computer control and data acquisition systems as an electrical engineer   , CAD/CAM with naval ship piping systems, hospital HVAC systems and building construction, retired out as of all things, a civil engineer of which I am not   I guess there isn't much difference between pump curves and Portland cement slump   plus spent first 3 years in the Army as a 02J clarinet player retiring and collecting a reservist pension with a small active Army retirement at 60 a year ago, which confuses the heck out of people when I play jazz for them   ), you can kind of see that sometimes I must expend this built up gas in my system.  

Actually George my explanation of ABN/ABC was simplistic, but advances in precision machining to permit finer surface finishes and tapering along with tighter fit. The advantages of quick break in with this new technology is what I was referring to. No, there was careful thought, no one wants to lose their shirt unless the improvements helps to sell engines. Even Fuji oddly enough went to ABC technology on their 099S-II cross scavenged engine, the only one as the other sizes they had were Schneurle.

I gather the author of that rat race piston swelling method was referring to a worn McCoy engine. When it no longer had adequate compression, he tried this method, and it work. I guess it is just one of those things and felt that there was nothing to lose.

In a way, Cox's methodology was similar. I remember the break in instructions on engines and RTF planes back from the early 1970's, it was broken in after a few runs. I'd see metallic content in the glow fuel exhaust oil during the first run, the broken off bits from fine honing. It was this finer honing and better fit that along with lower cost helped Cox to dominate overall half-A flying. After a run or two, one was ready to fly.

ABC/ABN technology was similar, after a short break in, engine was ready to fly.

I came across a Peter Chinn review in American Modeller circa 1968. While I'm not a fan of Peter's reviews I feel they're a guideline for those interested but more a marketing tool. I can fully develop my own opinions. If you read them thoroughly, you see very little of the negatives. But, this one took me by surprise. This was in regards to the red head .19 and also .35's. While the review was being conducted, the engine that Peter was using took a dump. Now to his surprise ( I don't really know why) he felt the need to use another example in which it also took a dump. He contacted Duro- Matic which claimed, ready for this, the materials they used were sub-par and the engines were rapidly wearing out prematurely. The solution was to hard chrome the piston which they supposedly did for the .19 super stunt. I've yet to see one but I'll bite. Peter graciously wrote that the engines were properly broken in and the correct oils were being used. Ken

Ken, I know what you mean, in other words, Peter Chinn had an eloquent way of saying that the engines as received sucked, LOL. It was interesting that it was a Duromatics, was this at the time Testors purchased Duromatics?

There was someone in the cottage industry who would chrome plate a McCoy piston, which then provided a superior engine with long lasting qualities. Don't know anybody now doing it.

As a writer he didn't bite the hand that fed him, also said of engines such as the Fox 09 Rocket about it being easy starting but not a powerhouse but in a manner one could conclude this may not be a worthwhile venture to purchase.

Best of the engine testing write ups was Peter's test data, metallurgical explanations and analysis, props and RPMS, HP and torque curves, etc. Those I really enjoy reading on.

What caught my attention here was this review was based on the Lightning bolt case. The review boasted about how great it was. Not that I'm not a fan of that case, that really wasn't the issue at hand with that engine. The internals didn't change, I agree that the case gussets not to mention the bronze bearing were a positive move. What puzzles me here is how the review claimed that the super stunt redheads now came with hard chroming on the pistons. I've never ever seen this and I've seen a lot of them. The review said that there was absolutely no difference between the red head and blue head r/c versions internally speaking. While the company went out of the way to offer a better product, certain QC issues were not properly dealt with. This initially led me to believe that the review was comprised on the lightning bolt case and it's introduction. That's a heck of a way to introduce a new engine with internal parts that wear out before breaking in. But, problems were already surfacing prior to the release of the engine. I don't have a scanner to show the article but it claimed that the new piston offerings absolutely solved the problem. I can't comment on the who owned who or when. Peter stated that the Duro-Matic company was contacted in regards to this issue. The response was that they had seen the problem in the .19 and a few of the .35's and the problem had already been addressed. This review is totally contradicting to another Peter Chinn Mccoy review I've read.

Given that model manufacturers need good reviews to sell engines and magazines need the support to sell magazines, can't say specifically, but imagine that the editors had input into Peter Chinn's articles. Given that Peter did reviews for other engines probably kept him very busy, along with the others things he had to do in the industry. With an ocean separating the countries, it could be possible that what Peter received could have differed some from the domestic offerings. Also, the differences in time when first article was written and another could have left Peter with a different perspective after running another set of engines again.

I guess the jest of it all is, we are here where we are today. Engines more or less have become historical collector items, and what is left is what we fly with. That leaves us with making our own decisions, but now with a better basis as there is more information out there than years ago when some were going through the school of hard knocks for learning.

As with anything, we all have choices. If over time I become disenchanted with McCoy's, I can always go for another engine. That's the nice thing about our freedom. About the only thing that might affect is a total banning of IC engines because of changes in law, locally or otherwise.