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I have a vortech V3 supercharger on a 1993 5.0. It has ported and polished heads and intake. Aftermarket exhaust and a Pro M efi system with individual coils on every cylinder. I'm running a 3.25 upper pulley and a renegade crank pulley. It has a stock cam and I shift at 5300 rpms. What gap should the spark plugs be for this combination?
 

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Depends on the ignition system components. But to hazard a guess... .035
 

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Discussion Starter #3
Gap

I'm using the same coils that is on the Corvette ZR1. ProM stated that I wouldn't need a ignition box with this setup. Thanks for the reply.
 

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Not to define the size of gap, but what plug are you going with? I would stick with Motorcraft 32 or NGK, a lot of others go with Autolite.

example:
"The stock plug was Motorcraft ASF42C, which is equivalent to Autolite 25.
One heat range colder is ASF32C or (Autolite) 24.
Two heat ranges colder is ASF22C or 23."

Gap I would suggest max .035", could go as low as .028" depending again on ignition system and how much boost.

Another example, more detailed:
http://www.theturboforums.com/showthread.php?t=281795
 

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I have my gap set at .025" running NGKs
I set all of the supercharged cars I have & work on at .025. NEVER have to go back and reset due to "spark blowout or?"!! Also I have found in my MANY years of experience that Autolite 23's R TOO cold for the street. Just my experiences...
 

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What about the plug gap when running EDIS8? My understanding is that this ignition is really hot. Most OEM calibrations call for gaps around 0.060" and the like. Still 0.035" under boost?
 

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Once you add boost to the mix and pressures go up, it's harder for the spark to jump the gap. Most guys will mostly agree, .025"-.028" is the best gap to prevent spark blow out on 95% of the cars no matter what ignition your running.
 

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i am running 30 with pro-m and cnp with 12 lbs with no problems. i think you could get away with .035.

I ran 15 psi with a Vortech and never worried at all about gap. I just used .035. Used OEM ignition with MSD TFI coil.

Now I run a turbo. I was running the same OEM TFI coil stuff at 22-25psi and 7K RPM, but decided to go CD ignition and crank trigger when I stated running more boost and 7500 RPM. Still running around .035 gap, still never have a spark issue. I can run the plugs for months.

I'm running NGK V-power race plugs because I have not had a problem. I always use a non-resistor plug. :)

IMO if you have to tighten up gap at 15-25 psi, you have another problem besides blowout. You have something weak or wrong in the ignition or fuel if getting gap at .025 makes a car work and at .035 it won't.
 

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I ran about .032-.035 gap at 20 psi with C-16. Went to Pro E-85 and had to tighten the gap to about .022-.025 to stop the miss-fire. I think it had more to do with the volume of fuel put into the cylinder than anything else. With the C-16 and the 225 lb/hr injectors I was at 48% duty cycle. Now with the same injectors on Pro E-85 I am seeing 70% duty cycle. A lot more fuel in the cylinder for sure. Same spark plugs, NGK 9
 
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