Spark Plugs Closing Up ???

Discussion in 'PSI Superchargers Tech Questions' started by Sidewinder, Jun 9, 2006.

  1. Sidewinder

    Sidewinder New Member

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    HELP , last 2 passes on a 518 KB , blown alky engine , i have had 2 spark plugs close up from .020 gap to .002 & .007 , no way the piston is hitting them , i have bout .450 clearance , NOW i did run it REAL lean on these 2 passes , blowing the burst pannel ..... Could the plugs get hot enough (red hot) to have the compression close them up ????? I have been running this motor 2 years & never this problem .... Thanks for any reply ....
     
    #1
    Sidewinder, Jun 9, 2006
  2. Mike Canter

    Mike Canter Top Dragster
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    Compression will not close them up because the force is equal from all sides. Detonation will close them up because the force of the shock wave is coming from one direction. I would check the upper rod bearings on those cylinders and see if you are or have been detonating. What does the oxidation area look like on cadium? Where is the blue line on the plugs ground straps? What are the EGTs?
     
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    Mike Canter, Jun 9, 2006
  3. Sidewinder

    Sidewinder New Member

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    Spark Plugs Closing Up

    Thanks for the reply , i don't run EGT's .... Just run 100 yards in the sand , To much money for me ......Ground strap is blue bout all the way down , cadium is discolored bout 1/4 of the way around , haven't checked the bearings yet to see if they are getting smashed ....
     
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    Sidewinder, Jun 9, 2006
  4. Mike Canter

    Mike Canter Top Dragster
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    If the the ground straps are blue all the way down then there is a possibility that you have too much timing in the motor and you are detonating. Do you have a digital camera and if so take you take good high resolution close up pictures of the ground straps in those cylinders and email them to me at mike.c@mindspring.com.

    Have you checked or changed your timing lately?
     
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    Mike Canter, Jun 9, 2006
  5. Sidewinder

    Sidewinder New Member

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    Spark Plugs Closing Up

    Thanks Again , I Will Get A Picture To Ya , I Should Mention I Did Increase Timing To 32 Deg From 30 , Plus I Changed The Blower Overdrive From 59 To 72 Over , I Fattened It Up But Don't Think It Was Enough , I Run A Ssi 14-71 High Helix Roots , Usualy Get 36 Lbs. Boost & I Needed A Lot More Speed For My Last Round So Thats Why I Tried The 72 Over , Don't Know What Boost It Made Because It Blew The Burst Pannel & Pegged The Gauge , I Think I Run 11 To 1 Compression , Only Turn It 7500 Rpm . I Am Pretty Much A Rookie With A Hemi It's A Lot Different Than A Bbc ....
     
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    Sidewinder, Jun 9, 2006
  6. Mike Canter

    Mike Canter Top Dragster
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    Wow, that was a lot of changes at one time. That was a major change in OD. I would recommend going back down to 59. With a increase from 59 to 72 is going to cause you to really heat the incoming air charge and make it prone to detonation and lower the power. For each pound increase in boost you need around .25 to .3 GPM increase in fuel. So what kind of boost do you think you had a 72 OD? Plus you advanced your timing 2 degrees. I would say go back to you known tuneup and work up slowly maybe one pound change at a time. If you make 36 lbs of boost at 59% OD it might be time to re-stripe the blower.

    The burst panel may have gone just because it was old. We change ours on a routine basis because the flex in and out and fracture after a while.
     
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    Mike Canter, Jun 9, 2006
  7. secondwindracing

    secondwindracing top alcohol

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    hey guys do you think that the blower is way to far on the over drive? it seems to me after you go so far the blower starts to not work, remember this is not a screw blower.mert and lee littlefield always told me after so much over drive you start to defeat and the air is making to much heat and you loose performance as for lead 32 deg. should be fine..At over 70% over drive that would scare me...............lots of heat. Let me know what you find out

    good luck Dave Lowe
     
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    secondwindracing, Jun 9, 2006

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