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Greg Ondayko
 Post subject: Spark Plug Indexing
PostPosted: Thu May 07, 2009 8:23 pm 
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What is the correct way to index the plug?

I would think Ground electrode 180* from intake valve location.

Thoughts?



Greg

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63Dart170
 Post subject:
PostPosted: Thu May 07, 2009 8:27 pm 
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I'm not sure how to answer your question, but congrats on the spread in Mopar Muscle!
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stonethk
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PostPosted: Thu May 07, 2009 8:51 pm 
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I read somewhere the electrode should be centered toward the squish area, supposedly that keeps the flame front somewhat even (spreading towards the far side).

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Joshie225
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PostPosted: Thu May 07, 2009 9:09 pm 
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I don't think it matters much in a combustion chamber as open as ours, but the flame should travel towards the exhaust valve first so the gap should face the exh valve.

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stonethk
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PostPosted: Thu May 07, 2009 10:07 pm 
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Why towards the exhaust :?:

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emsvitil
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PostPosted: Thu May 07, 2009 10:09 pm 
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See my old thread:

http://www.slantsix.org/forum/viewtopic ... g+indexing

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Joshie225
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PostPosted: Thu May 07, 2009 10:39 pm 
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Why towards the exhaust :?:
Because the gasses are hotter over there at the exhaust valve.

If the flame front starts at the cool end of the chamber then it's more likely for the air and fuel near the exhaust to spontaneously combust (detonate). This is because the chamber pressure rises during the combustion process and further compresses the gasses near the hot exhaust which can lead to detonation. If you start the burn in the hot area you burn those gasses before they are compressed to the detonation point and are therefore more likely to have normal combustion.

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slantzilla
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PostPosted: Fri May 08, 2009 3:28 am 
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The only reason we ever indexed plugs at the race shop was to keep the piston from hitting them on motors with big domes. Other than that there was no gains seen. :shock:

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Greg Ondayko
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PostPosted: Fri May 08, 2009 1:51 pm 
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I'm not sure how to answer your question, but congrats on the spread in Mopar Muscle!

Thanks! I went to TNT last night and a few people recognized the car from the feature too!

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defrag010
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PostPosted: Sun May 10, 2009 5:12 am 
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Indexing the spark plugs on a slant six is like a rocking chair. It gives you something to do, but it won't get you anywhere.
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