plug reading question

Discussion in 'PSI Superchargers Tech Questions' started by 94outlaw, Mar 24, 2010.

  1. 94outlaw

    94outlaw New Member

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    im new the the blown alky combination and have a question about plug reading. i took my car to the dyno today and after the first run i pulled the plugs. 6 of the plugs had timing marks on them. 4 just before the bend, 2 in the middle of the bend, but 2 plugs cylinders 5 and 8 had no marking on them at all. they still look brand new out of the box. what causes this? are those cylinders so lean that they are not burning? this is a bbc with a 1471, any advice would be greatly appreciated.
     
    #1
    94outlaw, Mar 24, 2010
  2. Mike Canter

    Mike Canter Top Dragster
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    My bet is what you are looking at on the ground strap is NOT timing marks if the rest of the plugs look like they are brand new. Just a guess I would say that your motor is way rich so the cylinders are way cool so the only thing that could heat up was the thinner ground strap.

    Try reading this plug reading article and then match what you saw on the dyno to the article then come back if you have more questions.

    http://www.dragstuff.com/techarticles/reading-alcohol-spark-plugs.html
     
    #2
    Mike Canter, Mar 25, 2010
  3. 94outlaw

    94outlaw New Member

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    does anyone have any pictures of plugs that i can look at, or is there a website that has some? the marks on my ground straps are blue with the cad burned back to the bend on the plugs that have marks on them.
     
    #3
    94outlaw, Mar 25, 2010
  4. Mike Canter

    Mike Canter Top Dragster
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    You can't read the timing mark on a plug until the base ring coating has burned off the plug correctly. The fuel mixture has to be close to correct before the blue line is correct.
     
    #4
    Mike Canter, Mar 25, 2010
  5. aj481x

    aj481x Member

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    Reading plugs on a dyno is very difficult. Watch the EGTs, fuel flow and BSFC.
    A dyno will not give you a race tuneup. :cool:
     
    #5
    aj481x, Mar 25, 2010

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