Didier

757jonp

My Feedback: (48)

Oh I read that post, actually I've read every post several times! What's buggin me is I find it difficult to believe that Saito would goof up the machining on that master rod unless it was deliberate for some reason I can't fathom.
The video in post #2022 doesn't really make it clear whether the magnets were spaced at 120 degrees or 126-126-108. You'll notice he's bringing each cyl to TDC, then checking them at 30 degrees advanced. If the ring magnets are set at 120 spacing that would indicate the crank is also phased at 120 degrees. (as it should be IMHO)

Took me awhile to get the proper tools, but I'll be looking at mine shortly....

elmshoot

My Feedback: (6)

The angular difference in TDC between the cly is the result of a single master rod. The other two rods are attached to the master rod. I am sure there have been other ways to do this but it is the only way that a Radial is reasonably feasible.
About 99% of all radials share this design "shortcoming".
The ignition timing is normally accounted for this "shortcoming. Apparently this wasn't so in this engine or the designers decided there was little to be gained in doing so.
Sparky

cathurga

Sparky,
That about sums it up, and in full sized engines, I am sure they accounted for that with the ignition system making some compensation. I also agree that it is not going to be critical, UNLESS, the timing on No1 is advanced to around 50Deg, it means that No2 was then at around 56Deg....and thats significant, and most likely (IMHO) one of the reasons for that one to try and 'blow its lid off'.
I spoke with Morris late last week, and he admitted he doesnt join the forums much, mostly because he doesnt want to get embroiled in arguments with people.He's a genuinely nice guy, and loves what he does, he's an asset to the rest of us so I respect that decision. He did say that he had been contacted by people around the globe about the timing issue, and got back to me as well, to find out if these findings were right. I certainly dont want to try and pass myself off as an 'armchair expert', and challenge the mighty Saito, I wouldnt dare....they have been doing this a long time. BUT, all the problems we have uncovered as a community, appear to be ignition related, and I simply dont see them as experts in the gas engine realm. This is why they have chosen to select Walbro technology in their carbs, and Rcexel in the ignition systems, but it seems they have not adapted well enough to the technology with their engineering. No finger pointing from me, and I am not going to be picketing outside their factory wanting, nay, demanding compensation. Nor will I raise a lawsuit.
This is also why I have offered to be a guinea pig, and blow up my engines if I must, just to confirm an engineering standpoint with regards to ignition timing, and that is that ignition should be at around 30deg at its most advanced state, in order to offer good power, and longevity.
Morris is making the rings at 126/108/126.
I am quite convinced it will NOT increase power, hell, it may even REDUCE the power, .....I dont know. But I AM convinced it will run well, and wont grenade any cylinders....and thats what I want from my engine. I think we are all in the same boat,right.

May I also say, that I would be quite happy, and grateful if all of us could be having this chat, in a bar.....holding pints of our favourite beer, and sharing anecdotes....for now though, we hang out in cybr world.

CHEERS!

Andy

F3A Nordic

757 Jonp
I think it is clear that this engine TDC Spacing is not 0, 120, 240.
Several people have checked ther engine's and have same result.
This is my First radial engine and i am also surprised finding this but have now accepted it and
have manufactured a new prop hub.
I have many glow engines 2-stroke and 4-stroke OS and Ys and have not needed to manufacture modified part other than exhaust system. I think this engine have 3 issue. Timing from factory 45-50 degree Tdc and not possible to adjust close to 30 degree. Various timing on each cylinder. Intake design not perfect ( cylinder 1 lean and cylinder 2 and 3 rich).
Cooling fins are not big and engine need proper baffling to have low cylinder temp
Timing and intake issue can be solved.

The engine have great sound and are perfect for scale airplane If it is not to heavy.

elmshoot

My Feedback: (6)

See my post above, it cant be 120º apart.
I am still the Doubting Thomas in that no one has dynamically checked the timing, ie; strobe light while running. hard data, before and after modification, not "it seems to run better at a different timing". Is the only way to verify that you have a problem and have fixed it.
All that being said if Morris makes a magnet ring with the appropriate timing adjustments Ill buy one to check out.
Sparky

757jonp

My Feedback: (48)

Granted... the master rod rotating on the crank changes the angle on the articulated rods. One would alter the attachment point to compensate for it when designing the master rod. (radial design 101). Anyone want to guess what the cam timing looks like?

cathurga

757jonp you're 100% right on the design comment. Ive not flown a lot of glow engines, but I would be cautious in saying that it might not be as critical in a glow engine, an area where Saito are the experts. Does glow not go on when the compression decides the burn rate? If so, then it doesnt matter where the crank is, provided the compression is happening in each individual cylinder, at the right point, then you are good to go? (my deduction is steeped in caveats, since I am not really sure).
In a gas engine, an area where Saito still has some learning to do, the crank position and ignition point are a more critical factor. After all these are really glow engine designs, that have been converted to gas as far as I am aware. The ignition point in this application, is a shared point on the ring, where individual clyinders rely on a common timing point (i.e the magnets poistion in relation to a single sensor)

With regards to the induction/valve timing, the way that the timing gear is timed, is by setting each cylinder to TDC, and then placing the cam in the right position. This is done individually, regardless of where the other cylinders are, so it is not dependent on spacing between cylinders.
The only cam issue would be the 'shape' of the cams, and their position on the cam gear, but I dont think it is out by any measure. The only way to check that is to measure their lift, rate of opening, height of lift, overlap etc etc.....thats a whole different art form and I dont even want to go there. It seems to me this is more of a performance tuning requirement and I am not going to go down that road if my engine is running well and reliably.

757jonp

My Feedback: (48)

cathurga... Your spot on. If this engine was running on glow it wouldn't matter where the crank was. It would act just like 3 FA-125's on a common crank! I've threatened my engine by waving a gallon of glow fuel at it a couple times, even went so far as throwing a carb repair kit in glow fuel to see if it was ok with operating on methanol (it was/is). I'm not thrilled one bit about running this engine on glow, and all the nasty mess that entails, but I'm sure it'd run just fine.

I only see one part # for the cams, so I presume they're all the same. IDK how you would adjust them to compensate for differences in timing between cylinders, the gear mesh is way to coarse for that. I would suspect that the cam timing would be different for all 3 cylinders. No 1 would be ok, of the other two cyl, one would be retarded and the other advanced??? No wonder the cylinder temps are all different!

cathurga

757jonp

My Feedback: (48)

Why not? You afraid it might run right finally....? LOL Actually mine's been running pretty good on 100LL and 15:1 Klotz. When I say "pretty good" I've always thought it was a little "off" and could be better.

. Anyway I got around to digging into the engine to see whats what for myself. Using a degree wheel and a piston stop set about halfway down the bore I took readings in degrees and calculated TDC for each cylinder and came up with 1-2 @ 126.5, 1-3 @ 126.5, and 2-3 @ 114.0. That totals 367 degrees of rotation! I'm sure the error comes from the changing angle of the master rod right to left as you observe the readings. Lightly bumping against the stop I got 123, 123, and 114 (360 total). Ignition timing is at right about 50 deg BTDC

I plan on repositioning the sensor mount to get it around 30 deg BTDC and call it a day. Should run more better!? If not I've got a pretty good stockpile of glow fuel. LOL

cathurga

cathurga

Well, gentlemen, I am sitting here at my dining room table, about to tuck into a HUGE portion of humble pie! Cylinder No2 let go earlier today in mid-flight. I will go into more detail later once I have access to the pics that I took. I need to do some more inspection before I come to any conclusions, but have already done the tear down of that cylinder, and it is quite surprising that the engine kept running. There was a very audible noise when it went, sounded like a misfire, but with more 'clang' in it than would be expected from a misfire. Landed the plane promptly as it was clearly running on 2 cyl's. As it taxied to a halt, it was still running but sounded like a marble was in there. Shut it down and noticed that No2 plug lead was off. Before the last flight, we did some tuning to the engine as previous 4 flights had showed some strangeness. It started, ran well and was fine, but after a while it got warmer, and started dropping a cylinder (assume to be number two) a week or so ago, we undid the spark plug on 3 and it disintegrated. Put a new one in and it was still running erratically. I have heard (and experienced, to some degree) the LS needle moving on its own and I thought that it was running too rich. I leaned up the LS and it got into its good rythym, and was going like a train again. Sent it up for the last flight and it did 4 circuits and was sounding sweet. The peanut gallery at the club were standing around admiring it. Temps on Cyl 1 was reaching 140 C max.Next circuit....bye bye cylinder.
It should be known at this point, the timing was at 30Deg and from what I can gather, the timing had not shifted. I need to check as part of the post-mortem, that the timing was still the same. This engine was purchased from someone who had previously had Cyl2 rebuilt by HH under warranty. I know that he had run the engine when he got it back from them, so it was not new to me. I have also probably put over an hour of time on this engine since I bought it from him, and probably another two hours since. The timing was changed a few weeks ago, and I would estimate that its done at least 20 flights since I changed the timing. It was running a Keleo exhaust.
I am bitterly disappointed, not least of all with myself, for banging the drum about the timing. I still think the timing is wrong from the factory, and I will KEEP running my engines with this timing. It simply appears that either this engine was carrying an existing problem, or the timing is not the only factor in the cylinder breaking problem.

I will post pics later, but in the interim, you guys are free to point and laugh all you want, LOL!

I, on the other hand, will be on the net, ordering another cylinder, valves and a new ring. Because I am not going to stop with this until I am done.... :-)

elmshoot

My Feedback: (6)

Hey thanks for the report,
were you running the bigger 4 blade propeller as well?
If so what was MAX RPM?
Did this engine have the grooves in the top of the piston?
Sparky

cathurga

cathurga

Ok, here are some pics from yesterday. And some rather disturbing discoveries about carbon build up....

First the cylinder crack. You can see it in place, as well as when I removed it. Obviously the crack looks worse once its off, but remember, this thing was still running when it let go....I also took a snap to see inside the crankcase, seems like there is plenty of lube in there...



Left View


Right view


Oil sloshing about


Rear of cyl - Removed


Front view - Removed

cathurga

Now what I find disturbing.....look at all that carbon, the exhaust valve is in a VERY bad way.....this is with Redline at 20:1....

What the H.....?


Exhaust Valve


Inlet Valve


Exhaust Port

the pope

What oil was used in that ?

F3A Nordic

Cathurga
Sorry for your engine break down.
Yes that's a lot of carbon in combustion chamber.
Is it same on all cylinder, i can understand if don't want to remove all cylinder to check but i think you have to clean all valve's on each cylinder.

Any damedge on piston or piston ring.

cathurga

757jonp

My Feedback: (48)

Cathurga-- Sorry to hear about the engine failure, you can only hope that the damage was started prior to the timing change. Still, it sucks. I've also noted carbon buildup in mine, particularly on #3 cylinder that's always been the hottest for reasons unknown to me. When I pulled it into the shop the other day the exhaust valve on #3 was stuck. A little carb cleaner freed it up, but now I wonder if I ought to pull it down and inspect it further. Was that cylinder running the hottest on yours? Looks to me like a classic case of overheating leading to detonation and failure at the weakest point as discussed here before.

You mentioned something about the low speed needle not holding position? I had that same problem with mine and I'm wondering if it went lean during a run leading to the failure.

There's no reason for a dose of humble pie, but you insist, I recommend topping it off with a big dollop of cool whip on top! I speak from experience, for I've eaten my share. LOL (the latest was over the use of steel pistons in late model Detroit Diesel engines of all things)

elmshoot

My Feedback: (6)

The carbon Build up will increase the compression ration on the engine. We would do that intentionally on or G-62 to increase the performance of the engine when used in racing a stock engine.
You have already mentioned that you think the engine is over compressed. How many gallons of fuel did you run through in this engine.
I would think some time doing a full teardown and decarbon the engine as part of the rebuild.
Keep at it!
Sparky

cathurga

Sparky,
I agree, it would make sense to take the other cylinders apart and do a de-coke on the whole lot. Its just a PITA that you have to get a gasket set everytime, and they arent that cheap (for me, where I have to buy everything int'l). What makes things worse, is that for shipping on the parts I need, HH will charge me double! I do hate them sometimes.
One of the things I have come to dislike about these Saito engines, is you cant just take a cylinder head off, you have to take off the back plates, remove all the pushrods etc. The UMS engines you could do a top-end de-coke very easily. They have a seperate cylinder head.

I dunno how many gallons through this thing before I owned it, but I reckon I have put more than a gallon through it. The previous owner had put in some self-made gaskets in it, and I didnt like that, so I bought a new set and put them in, just when I got it. When I say I have put a gallon through it, bear in mind that a 500ml tank of fuel gets me about 15-20 mins of flying, so a liter would get me around 35mins, and times that by 4 and you've got 2 hours of flying. I would guestimate 3 hours on it since I've had it.

Before the last flight, I had to lean it up on the low-end, as it was stumbling a bit, and transitions were accompanied by bursts of blue smoke, so it was rich for sure. The last flight was really going nicely, and as we had done some tuning, the cowl was off and temps never got over 140C, so overheating unlikely, and it didnt sound like it was leaning out. I may have a look at the carb settings and see where they were.

Jon, be aware, a tear down means you WILL replace the gaskets under the jugs.

Anyway, I am involved in an exhibition this week, so unlikely to get much done to it, but I maye have a look at removing another cylinder and having a look, I think I have a pair of gaskets so will take the time to have a look in No1, as its the one that runs hottest and leanest of all of them.

757jonp

My Feedback: (48)

Would you get a better deal on parts and shipping through Morris Minimotors considering the part of the world you're in?

Speaking of Morris... I was looking at some of his videos today. I see that new intake of his evidently opens up the intake plenum into the crankcase similar to the way the Evolution radials are setup. Pretty dam expensive little chunk of aluminum though!

Those that have ordered stuff from Morris... do we (US) have to pay that value added tax or not?

khoysagk

My Feedback: (2)

We do not.