Which plugs? 781 big block....

Discussion in 'Troubleshooting & Diagnosis' started by Soundwave, Jul 31, 2017.

  1. Soundwave

    Soundwave New Member

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    So, ive been all
    Over this car chasing performance issues, car wont move under full throttle.... super flat acceration..... list if parts:
    781 heads, mild cam and flat top pistons, so low comp.... but....
    Replaced fuel pump and filters
    Hei dist, then added msd 6a
    3k stall with 373s
    Plug wires....
    But, getting mixed plug recommendations... the ones i have now come back for a lawnmower.. i had the r44ts, short reach, but idle was rough, put the mower ones back in, long reach 13/16 hotter plug..... just ordered champions
     
  2. Soundwave

    Soundwave New Member

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    CHampions 57yc? 5/8 long reach....
    Timing is at 10, any higher and i get timing ping.. at light throttle at 2500 rpms... with 93 fuel.... plus rougher idle.... im beyond stumped with this
    Motor... almost feels like its not gettinf fuel, but has a new holley 850 (way too much carb, but all i had)
     
  3. 77Z28454

    77Z28454 Veteran Member Lifetime Gold Member

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    I've had good luck with Autolite 24's I'm no engine expert but 10 degrees of timing and having pinging seems low.
     
  4. Soundwave

    Soundwave New Member

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    Was pinging when i had initial around 12-14..... car not happy!
    Which heads are you running?
     
  5. 496z28

    496z28 Veteran Member Lifetime Gold Member

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    I had the same problem with my dually. Never got it figured out. I was running NGK UR5 plugs.
     
  6. Soundwave

    Soundwave New Member

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    Pretty sure this isnt my problem, but worth a shot! What was yours doing?
     

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