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Addicted to oil
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3,292 Posts
Discussion Starter #1
What gap should I do for Autolite 3923s? 500+hp, 25psi, 110oct.

30 sound right?

Thanks,
Dennis
 

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Addicted to oil
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Discussion Starter #2
Bump. Somebody must know.
 

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This Is Why I'm Hot.....
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1,984 Posts
More like .21 - .25
A 1/4" of gap is a bit too large, LOL.

Gapping rule of thumb:
Use the largest gap you can run w/o misfire. If you can get away with 0.030" , go for it. You may have to try several gaps before you achieve optimum.

Good luck.
 

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3,877 Posts
what he said ^^

hope you're good at swappin plugs...
 

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Resident Smartass
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on ngk 6097's ( cheap and work flawlessly) I ran a gap of .026 up tp 26psi,
Now I have them gapped at .018 at 35psi.

Like said above, you will have to play with them a little, I would suggest starting at 26-28 but no 30,
Catto
 

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Grumpy Old Man
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4,210 Posts
Larry: LOL :)

Dennis: Plug Blowout usually happens around Tq peak, if you have it drop the gaps 2 thou at a time and retest then repeat if needed.

If you get to 20 thou and it's still blowing out the spark try some more advance around that range(2>5 degrees usually clears it) , if this doesn't help it's time for CDI.
 

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use to always run autolite 3923's, they always blew up when doin big boost. I have NGK iridium (forgot the #) but they are gapped to 28.
 

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on stock ignition.. .024 depending on what type of 30 psi you are feeding the motor (ie 30 psi on gt35r is much diff than 30 psi on a gt4202rs)

If you can not live with smaller plug gap then you must go to CDI as IJ. suggested.
 
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