glow plug question

I just got a new OS 46 FX and broke in like the books say. I'm using 15%
nitro 18% oil and #8 glow plug , after about 4 tanks of fuel the plug was
dead, wouldn't glow at all so got out another new #8 os plug and put it in
and after 4 more tanks it was also dead so i put in a #3 os plug and ran it
about 5 minutes today and it ran ok. Any idea what is happening to the plugs
? Maybe i have it too rich still ? There is a hesitation when i go from slow
idle to full throttle. full throttle is great power on #3 or #8 plug. The
temp. is always in 80+ with some humidity. I been using top flight 11/6 and
12/6, master airscrew 11/6 props.
doug,
Reply to
doug
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Going on just the above, either you've been running way too *lean* and contaminating the platinum with bits of the cylinder liner, or the engine was full of machine shavings...
/daytripper
Reply to
daytripper
The motor has always had alot of oil coming out of the muffler and all down the side the the plane--Big Stick 40 and when flying i can see a smoke trail so i hope i didn't get it to lean. the hesitation happens when it is ran rich or leaner. Also forgot to mention that i took out the baffle in the muffler like the instructions said you could for more power.
doug,
"doug" wrote in message
Reply to
doug
The motor has always had alot of oil coming out of the muffler and all down the side the the plane--Big Stick 40 and when flying i can see a smoke trail so i hope i didn't get it to lean. the hesitation happens when it is ran rich or leaner. Also forgot to mention that i took out the baffle in the muffler like the instructions said you could for more power.
doug,
Reply to
doug
12 x 6 is too much prop 11 x 6 or even 5 much better....sounds like low speed needle is too rich for transition to be crisp
Reply to
Andrew Noll
I agree on the 12 x 6 prop being to much for a 46. Especially with 15 % nitro. The engine is probably detonatiing continuously which can easilly destroy a plug. Also, with this prop, it may be very difficult to set the needle properly as the engine has no real peak rpms. The engine will also have trouble spooling up with this big prop. I use 11 x 5 on all my 46s and they love it. I also use 5% nitro but we are at sea level and not 1000 feet above as you are Doug so I don't need extra nitro. Good luck Gene
Reply to
Gene
This is an ABC engine. Break in using only a slightly rich 2-cycle. If the piston and cylinder liner don't reach proper operating temperature, premature wear may occur.
12x6 is too much prop, as others have mentioned. The 11x6 or a 10x8 would be better.
The hesitation may be caused by an improperly adjusted idle valve. It's probably a little too rich, as is the high end. This will cause the engine to load up with fuel.
For the past 15 years, I have used McCoy RC 9 or 59 plugs. They are sturdy and clean-running.
Be sure you use fuel with a little castor in it such as Morgan's Omega. ABC engines like a castor/synthetic mix.
Good luck with it and keep us posted.
Dr.1 Driver "There's a Hun in the sun!"
Reply to
Dr1Driver
You didn't mention what you were using to lite the plug. I've seen power panels outputting too much voltage that shortens plug life.
Also if something is dissolved in your fuel container (lead for instance) it will render the catalytic effect of the plug's chemistry useless.
Mike
Reply to
Mike
The best prop I have found for this size engine is the APC 12.25 x 3.75. It's awesome!
Reply to
jeboba
That shallow pich prop works great for a 3D type plane, but it might be a little slow for some people's liking on pattern or sport type planes.
Wiz
jeboba wrote:
Reply to
Mike Wizynajtys
Amen to that. On a fun fly, it is stunning. Put it on a normal, low-wing sport plane and the engine winds tight, while the airplane flies too slowly.
-- Mike Norton
Reply to
Mike Norton
I would suggest going to 10% nitro or adding an extra head shim. Too much compression (either mechanical or by nireo) will cause higher combustion heat with no real increase in performance.
If you can, look at the glow plug element nder fairly high magnification. The surface should be smooth. If it is frosty or mangled, that is usually too high of heat.
As others have said, the 12X6 is a bit much for that engine. I would go to an 11X6 after resolving the glow plug issue as I don't think they are related.
-- Paul McIntosh
Reply to
Paul McIntosh

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