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Why do people put IC Engine cylinder fins back on wrong?


Paul Marsh
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You see them every now-and-then, mainly on ebay. I'm talking about why some poeple put the cylinder head fins back on wrong? Is it:

People don't know what they're doing and therefore a "Black Pudding Bender".

Maybe helps cooling in certain situations;

or maybe looks cooler...question

What do you think?

Examples at the moment...on ebay.

IC engine with wrong head, no. 1

 

No. 2

Edited By Paul Marsh on 08/07/2012 13:07:18

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It's so that we know not to buy them. It means:

1. They probably don't know what they are doing.

2. They're probably not very mechanically minded,

but worse of all, bearing the first two in mind...

3. They've had the cylinder head off!!!!

No, clear indication to leave well alone I think. Actually it's very considerate of them to send us this signal when you think about it!

BEB

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These pictures of cylinder heads trying to go in the wrong direction put me in mind of a little story, which I have related somewhere before.

It all started back in the depths of beyond, long ago, when we all struggling to learn how to get to grips with proportional control. Someone turned up at the field with an engine in a model which would start and tick over beautifully but would not increase revs as the throttle was opened. Eventually the engine was taken out of the model, on site, and the owner denying that he’d been tinkering with it; although he was known to be a bit of a fiddler. When we took it apart we decided that the cylinder liner was in sort of back-to-front, obviously one of the types without a locating peg, so we then put it back together and of course it now ran perfectly; and at this point the owner confessing that he had previously taken it apart.

Much later on, although still a long time ago, I had amongst others a fourteen year old pupil, a lad that was learning to fly. He’d got to the self-assured stage, starting his own engine etc. and was virtually solo. Dad dropped him off at our patch one Sunday afternoon, as usual, but soon he was saying “ Pete, would you have a look at my engine, please? ” The engine was starting ok but would not rev up beyond a fast tick-over, and was also making a curious muted plopping sound. So having taken just a quick look at it I told him that he had taken it apart and put it back together with the cylinder liner reversed. This he denied, but I knew that he liked to experiment, he’d previously told me how he’d taken his Grandfather’s lawnmower to pieces and put it back together; and other such adventures.

So I told this might be a little bit of a porky and that I’d take it apart again and show him. What I didn’t tell him was that I’d previously seen something similar anyway but the real obvious clincher was that the cylinder head was now on at 90 degrees to normal, a fact that he was completely oblivious to! So, in two secs we had the head off, I showed and explained to him the porting in the liner and how it worked, we reassembled it, cyl. head now going straight ahead and two minutes later he was in the air and flying as normal.

I’m not a big fan of the expression ‘gobsmacked’ but that might be just one rather trivial way of describing his reaction. He really really did not know what to say! He did admit then that he’d had a play with it but as I said before for about half an hour he truly thought I was God! Of course, I never did spoil that illusion by telling him that I’d seen something similar before or pointing out his deliberate mistake with the sideways pointing cylinder head!

I have to say, as someone used to looking at i/c engines, it does seem remarkable that these cylinder heads can be put on in various incorrect ways and nobody apparently noticing. But, by the same token, it might also amplify slightly the fact that sometimes it can be assembled partly incorrectly, and perhaps it does’t require much in the way of adjustment to fix it.

I think I would have to ask the seller why this is so, just to see exactly how convoluted the answer could actually get……

PB

Edited By Peter Beeney on 09/07/2012 14:26:34

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We had a chap in the club who put the cylinder liner in back to front. He did admit he had stripped the engine.

I once bought a Frog 2.5 cc diesel. It would start and run but when I tried to bring it up to power the piston hit the contra piston.

IT onloy took a few minutes to confirm my suspicions. The contra piston had been put in upsoiide down.

IT was a nice engine after that was corrected.

I have just put the listing for an Irvine engine with the head on at angle in EBay Sellers.

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Back in the day I can say I did this. I replaced the bearings in a Redline 53.

At first I did not notice the head was on wrong. When I went over the engine before fitting back in to my V2 Raptor the light bulb went off.
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I tell you what for all you guys waffling on, yes for sure it indicates the engine's been stripped, but I'd bet it would hardly make a degree or two of difference to the running temperature of the engine. When control line team racing we regularly used to machine fins off engines to get them to drop through bearers to facsilitate engine changes and bear in mind they were fully cowled installations, though admittedly well ducted.

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Posted by Ultymate on 09/07/2012 19:54:20:

I tell you what for all you guys waffling on, yes for sure it indicates the engine's been stripped, but I'd bet it would hardly make a degree or two of difference to the running temperature of the engine. When control line team racing we regularly used to machine fins off engines to get them to drop through bearers to facsilitate engine changes and bear in mind they were fully cowled installations, though admittedly well ducted.

Very true but it does indicate that the engine has been stripped, which is not good unless essential. It also indicates that the person doing the stripping doesn't know what he is doing which leaves one wondering what else has been fitted the wrong way round and what other nasties have been committed on the engine.

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Fair point Peter but on the other hand you could be looking at a picture of an engine that looks perfect externally (indeed it could be just a generic photograph) but be totally trashed internally which is the risk one takes when trading on ebay and the likes. "Buyer Beware" as the saying goes. crook Not the place I would be looking for engines at all. wink

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