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SpectraRyan

  • Karma: +2/-0
502 HO spark plug gap?
« on: August 11, 2017, 03:15:43 PM »
Hey guys, putting new plugs in our boat. Just had the heads cleaned and re surfaced and fixing a couple other things. Anyways my question is what plug gap should I run. I was told to use acdelco MR 43 plugs. It's a 502 HO BBC with a msd marine 6 blue box, Hardin billet distributor and msd coil.

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  • Boat #1: 1998 Advantage 27 Victory BR
  • Boat #2: 1975 Spectra 19 jet
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1998 Advantage 27 Victory
1975 Spectra 19
2011 Seadoo GTI130

Shocker_04

  • Karma: +17/-0
Re: 502 HO spark plug gap?
« Reply #1 on: August 11, 2017, 08:53:01 PM »
I have the 6al box and I run mine at 42. I also run the mr43. Not sure if it's the best gap but, It runs good so I leave it lol.

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  • Boat #1: 1980 Hondo 18'
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Shocker_04

  • Karma: +17/-0
Re: 502 HO spark plug gap?
« Reply #2 on: August 11, 2017, 08:53:52 PM »
Except now I have a slight misfire but, it's not because if the plugs.

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  • Boat #1: 1980 Hondo 18'
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GT Jets

  • Karma: +192/-0
Re: 502 HO spark plug gap?
« Reply #3 on: August 11, 2017, 10:02:53 PM »
It really depends on the compression ratio..... You will probably find .040" works great...

GT
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

SpectraRyan

  • Karma: +2/-0
Re: 502 HO spark plug gap?
« Reply #4 on: August 12, 2017, 09:18:15 AM »
It really depends on the compression ratio..... You will probably find .040" works great...

GT
It's stock wick I believe is 8.75 to 1

Sent from my SM-G920T using SoCal Jet Boats mobile app

  • Boat #1: 1998 Advantage 27 Victory BR
  • Boat #2: 1975 Spectra 19 jet
  • Like
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    Love
    HaHa
    Angry
    Surprise
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    Party
1998 Advantage 27 Victory
1975 Spectra 19
2011 Seadoo GTI130

GT Jets

  • Karma: +192/-0
Re: 502 HO spark plug gap?
« Reply #5 on: August 12, 2017, 10:06:38 AM »
It's stock wick I believe is 8.75 to 1

Sent from my SM-G920T using SoCal Jet Boats mobile app

Gap at .040" to .042" and let it buck... The difference between a gap of .035" and .050" will be completely immeasurable...

JMHO

GT
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

 


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