Spark Plug Gap? And Why?
06-30-2008, 06:47 PM
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Spark Plug Gap? And Why? Is there a reason to re-gap a plug in an LS1-LS2, LS6, etc motor?
I've been doing some research on this, but I haven't found what appears to be a 'definitive answer'. I'm wondering if there is an 'ideal' gap for a plug. For instance the stock plain vanilla delco plugs are pre-gapped at .060" if I am not mistaken. I am currently running NGK TR6 IR's that were gapped at .030" from the box.
I'm running what's in my sig and have re-gapped my plugs to .045" because someone who seemed to know more about it than me, (I don't know anything about it), told me so. I read somewhere that you should run the largest gap you can without 'blowout'. It was a while ago and I forgot about it until today because I was dynoing my 'new' LPE 403. The car made great numbers for what I was expecting. I know it's probably more of a tweak thing, but I'm wondering if there is an 'optimum' gap for a plug in a certain size motor, or for what compression ratio, or the kind of power you make, or for any combo of the above, or for no combo.
Will the flame grow quicker from a longer spark causing a faster burn? Is gap length more of a factor with carbed motors vs fuel injection?
I've been doing some research on this, but I haven't found what appears to be a 'definitive answer'. I'm wondering if there is an 'ideal' gap for a plug. For instance the stock plain vanilla delco plugs are pre-gapped at .060" if I am not mistaken. I am currently running NGK TR6 IR's that were gapped at .030" from the box.
I'm running what's in my sig and have re-gapped my plugs to .045" because someone who seemed to know more about it than me, (I don't know anything about it), told me so. I read somewhere that you should run the largest gap you can without 'blowout'. It was a while ago and I forgot about it until today because I was dynoing my 'new' LPE 403. The car made great numbers for what I was expecting. I know it's probably more of a tweak thing, but I'm wondering if there is an 'optimum' gap for a plug in a certain size motor, or for what compression ratio, or the kind of power you make, or for any combo of the above, or for no combo.
Will the flame grow quicker from a longer spark causing a faster burn? Is gap length more of a factor with carbed motors vs fuel injection?
07-01-2008, 07:55 PM
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Gap used to be very important with old point style ignitions. Our newer solid state ignitions put out enough voltage consistantly that gap is not "as" important in a pump gas N/A application. Gap becomes more of a factor on higher compression motors, high boost motors, and nitrous motors. A larger gap will indeed promote a "hotter" spark which can promote better burn, up to a point. Having said that, I personally feel that .030" is too small of a gap for your application. I would bet .050" - .060" would be more than sufficient. But I wouldnt get too caught up with plug gap.
09-30-2008, 10:51 PM
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The tr55 plugs that everyone raves about are gapped at .55 Does that give a hint. I have also noticed that the bigger the gap is on my plugs the more high end i seem to get... it also eats a lil low end torque. I guess its like everything else.... a trade off. Anyways sometimes it better to experiment for yourself and find your median. Just my 2cents.
