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Old 02-05-2009, 08:04 PM   #1
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Default NEED HELP 427 engine keeps killing glowplugs

Hi all
I am having issues with the 427 engine in my losi 8. I have tuned it to the best of my ability and i can hardly get through a tank without killing the glow plug. I have performed the pinch test and I am running the engine approx. 220-230 deg. I have also tried hotter and colder plugs to no avail. I am somewhat new to nitro as I am sure its operator error. Any sugestions would be greatly appreciated

thx
chris
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Old 02-05-2009, 08:09 PM   #2
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What plugs are you using? dont say hot or cold, give plug name and model # ex...Mcoy MC8, etc. what percentage Nitro fuel?
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Old 02-05-2009, 08:12 PM   #3
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It could be a lot of things, but I'll take a stab at a few. When you do the pinch test, the engine should run for about 7-8 seconds before it dies. If it's stalling too quickly, you're too lean on the bottom. The temp range doesn't seem too high, but the if the ambient temperature is very cold, then 220-230 might be very hot.

Be sure to use new fuel.

Check the top of the piston for a sandblasted look. If it's clean and has a fresh sandblasted finish, then you're getting detonation, which can take out a plug pretty quicky.

Don't run too much nitro. It can cause detonation as well, which will bury the plug.

Is the engine relatively new with good compression? A worn engine can be tough on plugs.

Any chance you can post a picture of your plugs? Sometimes the diagnosis is easier if we get to see what's happening with the plug.
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Old 02-05-2009, 08:18 PM   #4
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Ahh sorry,
I am using 30% Odonnell fuel.
Glow plugs I have tried McCoy mc-59.. Odonnell 99 and a os-8 .
When I remove the plugs they look good but they wont light. However the last plug I killed, Looks like the coil wire is smashed into the plug ??
thx
chris
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Old 02-05-2009, 08:22 PM   #5
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More info,
Seems the lastg few 59 plugs lasted longer but I would run a tank through the buggy and let it sit or about 10 min, refuel and try to start and it would pop a few times and die

thx
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Old 02-05-2009, 08:25 PM   #6
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Quote:
Originally Posted by SteveP View Post
It could be a lot of things, but I'll take a stab at a few. When you do the pinch test, the engine should run for about 7-8 seconds before it dies. If it's stalling too quickly, you're too lean on the bottom. The temp range doesn't seem too high, but the if the ambient temperature is very cold, then 220-230 might be very hot.

Be sure to use new fuel.

Check the top of the piston for a sandblasted look. If it's clean and has a fresh sandblasted finish, then you're getting detonation, which can take out a plug pretty quicky.

Don't run too much nitro. It can cause detonation as well, which will bury the plug.

Is the engine relatively new with good compression? A worn engine can be tough on plugs.

Any chance you can post a picture of your plugs? Sometimes the diagnosis is easier if we get to see what's happening with the plug.

I left my camara cord at work so i cant post any pictures until tomorrow. Sorry

thx
chris
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Old 02-05-2009, 08:28 PM   #7
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Quote:
Originally Posted by SteveP View Post
It could be a lot of things, but I'll take a stab at a few. When you do the pinch test, the engine should run for about 7-8 seconds before it dies. If it's stalling too quickly, you're too lean on the bottom. The temp range doesn't seem too high, but the if the ambient temperature is very cold, then 220-230 might be very hot.

Be sure to use new fuel.

Check the top of the piston for a sandblasted look. If it's clean and has a fresh sandblasted finish, then you're getting detonation, which can take out a plug pretty quicky.

Don't run too much nitro. It can cause detonation as well, which will bury the plug.

Is the engine relatively new with good compression? A worn engine can be tough on plugs.

Any chance you can post a picture of your plugs? Sometimes the diagnosis is easier if we get to see what's happening with the plug.

The temp inside the track facility is approx. 52 deg.

thx
chris
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Old 02-05-2009, 08:41 PM   #8
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I've always used an OS A5 in my 427. It's a very durable plug that I usually change in the 427 about every gallon and a half.
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Old 02-05-2009, 08:51 PM   #9
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I've always used an OS A5 in my 427. It's a very durable plug that I usually change in the 427 about every gallon and a half.
wow,
i will def give that plug a try.. I have gone through 4 plugs and havent even got through 1 gallon yet. but getting close

thx for the info
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Old 02-05-2009, 09:17 PM   #10
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Try 2 shims next time you run it, until you finish break in..that means, put 2 washers on the glow plug instead of 1
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Old 02-05-2009, 09:26 PM   #11
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thank you, I will try that as well
chris
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Old 02-05-2009, 09:49 PM   #12
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Quote:
Originally Posted by schultztec View Post
thank you, I will try that as well
chris

And IF you are still having the problem, put another head button spacer so that the plug is a little bit farther from the piston so it will run better
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Old 02-05-2009, 11:50 PM   #13
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The OS A5 is the perfect plug for the 427.
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Old 02-05-2009, 11:52 PM   #14
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The first thing I would do is get rid of the 30%, go to a 25% or even 20%. I put 19 gallons through a 427. It will make more then enough power on 20%.
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Old 02-06-2009, 09:00 AM   #15
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The first thing I would do is get rid of the 30%, go to a 25% or even 20%. I put 19 gallons through a 427. It will make more then enough power on 20%.
I agree! I wasnt even paying attention to the fact that you are running 30%. Your button might not be shimmed for 30% (not sure about that though), that would explain all your problems right there.

does anyone know if the stock shim height is good at 30%?
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