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OS 1.60 Blowing Glow Plugs

Old 08-15-2015, 07:45 AM
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Uncas
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Default OS 1.60 Blowing Glow Plugs

I have an OS1.60 in a 2 M Pattern Plane. Rebuilt the engine last winter with the following:Bowman Rings and New bearings. It has a Perry pump. I run a tank of 15% in it for break in - it runs great. After that I cannot get a Glow plug to last more than 1/2 a tank. I have added 5 shims to the head - thought maybe it had too high compression. It seems to blow when I increase throttle. I replaced all of the engine gaskets and the entire fuel system tubing. I use a glow starter that measures amps so I know I am not over amping it. Engine Temperatures do not seem high.
Using a 17 x 8 APC prop
I have Tuned pipe but it is pushed far back and it did the same thing without the pipe even attached.

I have gone through close to five OS type F plugs now. I am lost as to what to do. Could I have gotten a bad batch of glow plugs? Bought them from the LHS.
Old 08-15-2015, 07:52 AM
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blw
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Is the engine under a cowling?
Old 08-15-2015, 07:53 AM
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1QwkSport2.5r
 
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You're probably too lean on the needle setting. If you only ran one tank through it to break in the new ring, the ring isn't seated yet and will need a fair bit of rich running to get that ring to seat. Once the ring starts to seat, you can lean the needle out some. A new ring and bearings means you need to basically treat the engine as if it were brand new again and break it in carefully.
Old 08-15-2015, 06:29 PM
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Uncas
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Cowl is off.

For some reason the engine now runs. This at the peak of my frustration. I have spent hours on this one.

I don't know what happened. Same glow plug I thought was bad, started the engine again. I went out and started it and ran a tank full or more through it. Started right up. The idle was rough so I did richened up the idle mixture needle and it ran better. Perhaps low end was lean after all! I am confused - maybe the Perry Pump has some junk in it and it cleared. It is the only thing I haven't rebuilt though I did install a new vacuum line on it. I would not actually try to rebuild it, I would just replace it, but it seemed I always had fuel coming out the carb so I figured it was good. Not very scientific.

So atm I have only 2 shims on the head and the tuned pipe is set. Everything seems to run fine.
Old 08-15-2015, 08:00 PM
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1QwkSport2.5r
 
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Sometimes engines make liars out of their operators...

Kidding aside, about 85% of the time, blowing plugs means lean needle settings. 10% is bad bearings, and the other 5% of the time can be any other possible variable. IMO.

Last edited by 1QwkSport2.5r; 08-15-2015 at 08:03 PM.
Old 08-16-2015, 04:24 AM
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Os. Organized ****
Old 08-16-2015, 06:25 AM
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Take off the back plate and inspect for metal fragments.
Old 08-16-2015, 01:48 PM
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Problem not over.
Went to the field today to fly it. Started first flip and it was a back flip. Unbelievable. Taxied it to the runway and it died sitting there. Could not get it started again. Took the glow plug out and cleared fuel from it. Engine is inverted and this tends to foul the plug. Did this twice and the second time I stripped the threads. Last year I had a bad thread start and may have damaged them. Everyone at the field says bad threads are likely the problem. We'll see.

As far as OS goes I have found them to be very reliable until you get to the large ones - the 1.40 and now the 1.60 are troublesome. I fly Pattern so they see a lot of flights. Would like to change it out with a DA-35. Glow fuel and Glow plugs are expensive, not to mention reliability.
Old 08-16-2015, 02:15 PM
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MTK
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I suggest you ask these questions on the pattern forum. Many flew the 160 in competition. I believe your low end is rich now.
The D A 35 from some accounts is about as strong as a DLE35. I have experience with the DLE35 and the OS GT33 and between those two, the OS is far superior
Old 08-16-2015, 02:32 PM
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I've never had a 160 but I have had both 2 and 4 stroke OS engines.Is there a reason you're running an F plug instead of the suggested #8 plug? The F plugs are generally used on 4 strokes.
Old 08-16-2015, 03:57 PM
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Uncas
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MTK,
Yes, I agree.I think my low end is a little rich and adjusted it. Then I stripped the glow plug. I have a DA-50R which runs flawlessly, so I am inclined to go with DA. I have seen your threads in the Pattern Forum - nice work. I will consider the OS when the time comes.

Tom3097,
Not really sure why we use an F. The F is longer so I think it helps with inverted engine mounting (fuel pooling). It runs a little cooler. And I suspect that the Pattern guys came from YS 4 stroke experience. My 1.60 was set up like a 4 stroke with a big prop with high pitch and low RPM running a couple thousand RPM below the 2 stroke power curve. I changed that on mine to a lower pitch prop to get more torque in the vertical up lines and to slow it down in the vertical down lines and landings.

Jim West
Old 09-09-2015, 09:23 PM
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Burnt out plugs might be a symptom of running an engine too hot
Old 09-12-2015, 11:15 AM
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Default Os 160

Have you check with a different fuel with less nitro? I was running OS 3 or Enya 3 on mine with no issue.
Just my 2 cents
Old 09-12-2015, 11:25 AM
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Blown plugs result from bad bearings contaminating the element making them fail, lean mixture a more common cause, or poor quality plugs. An engine that's been run hot is one that's been run lean or improperly cowled (poor ducting) or both. If the plug element is distorted, crumpled, or melted, the cause is a lean run.

Too much nitro requiring too rich of a mixture will sometimes cause a plug to fail, but only because the extra fuel volume causes an overcompressed condition and usually crushes the plug element into the body of the plug.

Last edited by 1QwkSport2.5r; 09-12-2015 at 11:27 AM.
Old 04-24-2016, 07:26 PM
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Uncas
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A year later . . .
Put in a new Perry Pump. Went back to 5 shims. Switched fuel from Cool Power 15% to Omega 5%. Tuned Pipe backed out.
The goal was to lower compression.
It now runs like there was nothing ever wrong with it. 2 Tanks. This was it. If it failed I was giving up.
17 x 8 prop 8400 - 8500 RPM. I really need around 9300. The tuned pipe will add about 300 - 400 RPM.
So I will start testing by removing shims 1 at a time. This will increase compression. Will/Should it increase power?
Old 04-25-2016, 10:07 AM
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OS F plugs are quite hot for most 2 stroke. If concerned about inverted installation I suggest a cooler 4 stroke plug. K&B 4S is one. A Fox Miracle plug is a bit cooler but just a bit.
Old 04-27-2016, 06:53 AM
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Hi!
I would try a cooler plug! Like a Nova Rossi 4 or 5 or even 6 . Or... an OS 8 or Enya 3 or 4 plug. I think an OS F plug is way too hot and that is not the way to go when you run as much nitro as 15%.
Old 04-28-2016, 01:31 PM
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If you take Jaka's advice on using a cooler plug watch how your low speed needle reacts. Most likely you will need to lean your low speed some.
Old 04-28-2016, 05:37 PM
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Uncas
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Isn't the OS F plug the same temperature as the #8 ? Just with longer reach.
Old 04-28-2016, 06:18 PM
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Longer reach and larger element diameter. The Enya 3 is hotter than the OS 8/F.
Old 05-12-2016, 05:41 PM
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I use to run a similar setup on a H9 edge 540. OS 1.60 fx with perry pump. I used an 18x6 prop and an OS F plug. The F plug helps with the midrange throttling in this engine. I also never used more than 10% nitro. This engine likes lower nitro like 5 or 10 percent. You could try to run it with a regular muffler to see if the tuned pipe is causing the problem. An improperly tuned pipe will also blow glow plugs.
Old 05-12-2016, 07:19 PM
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Uncas
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sport10
Last Saturday I managed to get a run in with the tuned pipe moved up a bit. The RPM's peaked at about 8800 rpm. That is about 300 - 400 above what I was getting which about what I expect from this pipe which is the OS pipe for the 1.40rx. The wind was ridiculous so I did not stick around to move the move the pipe again. This Saturday I plan on making a few more moves on the pipe to get it tuned in. Rain and wind all this week. What a pain.

I am convinced I had too high compression for the 15% fuel and the pipe was also a factor in blowing the plugs. The stupid thing starts right up now like there was never a problem.
Old 05-13-2016, 03:13 AM
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1QwkSport2.5r
 
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One has to remember that a tuned pipe is going to increase the dynamic compression ratio - in some cases significantly. Since the engine is only part of the equation, the compression ratio, glow plug, fuel composition, head/squish clearance all come into play. To truly optimize the "system", you're trying a number of different things with each component to find what helps the engine make the most power and remain tractable. Piped engines tend to be harder on plugs, so going to a colder plug with a thicker element will likely help the engine run better and cold plugs usually make more power.
Old 05-15-2016, 09:33 AM
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I think the F is hotter. At least that's been the story for a long time now.
Old 05-15-2016, 05:29 PM
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The F in the 1.60 is how the pattern guys do it. The F plug stays hot longer; has to to stay lit during the two extra strokes of a 4 stroke. My YS1.10 will start even if the glow starter falls off; which it has been lately. Old stick and old F plug.

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