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Glow plug distortion?

Glow plug distortion?

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Old 12-24-2008, 12:22 PM
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The reason it sucks the plug in when the rod is worn is because the piston throws a litttle higher at top dead center and a little lower at bottom dead center causing a slightly higher compression. It is also i quick way to kill your motor cause of the tapered piston and liner it squishes the piston taper. When you do eventually change the rod your motor wont have the same performance.
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Old 12-24-2008, 12:24 PM
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Originally Posted by nitrodragster View Post
The reason it sucks the plug in when the rod is worn is because the piston throws a litttle higher at top dead center and a little lower at bottom dead center causing a slightly higher compression. It is also i quick way to kill your motor cause of the tapered piston and liner it squishes the piston taper. When you do eventually change the rod your motor wont have the same performance.
X2
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Old 12-24-2008, 01:25 PM
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Originally Posted by JAMMINKRAZY View Post
X2

I strongly disagree with this comment. Yes, a worn rod will allow the piston to drop a thousandth or so lower at BDC , but the compression of the engine (even a worn engine) will NOT allow the piston to come up into the head. All 360 degrees of rotation, the forces driving the piston away from the head will over come the piston's inirtia during upword travel). I run mod'd boat engins with 0.006" head clearance all season long without issue.

The element has been cooked by too much heat. This will be from a lean high speed needle or by a retarded (late) ignition where the fuel burns unevenly over a longer period of time than a "good" burn. A lean high needle with an overly rich low needle OR the late ignition will both create the wet look you see.

#1 check your needles to make sure they are correct. Not too lean on top and not too rich down low.

#2 once you feel the needles are good and you still pull elements out of the plug, try either a higher nitro (ie.: 20% to 30%) or lower the head (0.005" at a time).
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Old 12-24-2008, 05:26 PM
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Great thread, Great replies Heck I think I learned a lot.
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Old 12-24-2008, 05:35 PM
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Originally Posted by chunk t View Post
I strongly disagree with this comment. Yes, a worn rod will allow the piston to drop a thousandth or so lower at BDC , but the compression of the engine (even a worn engine) will NOT allow the piston to come up into the head. All 360 degrees of rotation, the forces driving the piston away from the head will over come the piston's inirtia during upword travel). I run mod'd boat engins with 0.006" head clearance all season long without issue.

The element has been cooked by too much heat. This will be from a lean high speed needle or by a retarded (late) ignition where the fuel burns unevenly over a longer period of time than a "good" burn. A lean high needle with an overly rich low needle OR the late ignition will both create the wet look you see.

#1 check your needles to make sure they are correct. Not too lean on top and not too rich down low.

#2 once you feel the needles are good and you still pull elements out of the plug, try either a higher nitro (ie.: 20% to 30%) or lower the head (0.005" at a time).
Actually I have had plugs blow out before because of con rod slop Not sure if that is his problem but it can definately cause distortion of the plug coil.
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Old 12-24-2008, 05:37 PM
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Too Hot!

The coil is distorted due to excessive heat.

If you have not done so, try the above plugs.

Check your piston, sleeve, etc. for wear. The pitting may mean little pieces may have broken off and that can cause the damage.

I would go back to factory settings on carb and start again.

good luck
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Old 12-24-2008, 05:44 PM
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Just alittle nugget from Ron Paris on how to "Read" your glow plug.

http://web.archive.org/web/200010020...m/glowplug.htm
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Old 12-24-2008, 05:44 PM
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I agree Chunk.

(1) Also as I said above: Go Tech engines are tuned opposite to all others. You do not set the HSN first and then set the LSN, which is what every tuning guide will tell you. A Go engine is the other way around and for general bashing you can even just leave the HSN at factory set!

I'd suggest that Herb goes back to factory settings and see. For a Gen5 Go Tech .21 with the all black carb and long LSN it would be HSN flush and LSN about 1.5 turns in from flush.

A race set would be no more than about half turn in on the HSN and 2 - 2.5 turns in on the LSN.


(2) sometimes people compensate for an incorrect idle gap but using the LSN to increase or decrease idle speed. That can lead to the low speed mix being waaay off and may explain a very lean HSN and very rich LSN (as we suspect from the pics)
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Old 12-24-2008, 07:06 PM
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Originally Posted by Djballen View Post
Just alittle nugget from Ron Paris on how to "Read" your glow plug.

http://web.archive.org/web/200010020...m/glowplug.htm
nice straight-forward link
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Old 12-25-2008, 11:50 PM
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Go engines are netouriously tight when new. So right from the get go you are working the rod harder than most engines. If it hasnt been changed since after you run it in and you have been doing high speed runs i would nearly bet my right crown jewel on the fact the rod has run its course. but then again i have never owned a a go engine. I've been wrong before.....
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Old 12-26-2008, 01:02 AM
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Chunk t speaks the truth!
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Old 12-26-2008, 02:47 AM
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To everyone that said it was the rod you were correct.
I dropped a new rod into it today and ran 3 tanks through it.
Pulled the glow plug out and it was in perfect shape.
The rod had not been changed from new and had just over 2 gallons on it.
Changing the rod after a engine has lost its metal pinch is something I will always do from now on.
I have learnt a lot from all the comments in this thread, thank you to everyone for your help.

Here is a video of it in action 3.5MB quicktime file

Last edited by herb99; 12-26-2008 at 02:58 AM.
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